In my games, I try to reach the endgame as soon as possible. I am good at opening, OK at middlegames but wonderful in endgames. Because of this I try to trade down pieces at high speed. So I select openings like Sicilian Defense and Queen's Gambit and Queen's Gambit Declined: Semi-Tarrasch Variation because of this. I use up a lot of my time on practicing endgames. So even if it is Queen vs Rook endgame and I was the player with rook, I have 92% chance of drawing the game and a 0.002% chance of winning the game.
"Do you think openings really matter that much? ♟️"

People on chess.com typically invest WAY too much of their time on memorizing lines.
Then when they reach the end of their memorized move-list, they play like a chimpanzee.
If they trimmed back their opening study to about 10% of their time invested (as LieutenantFrankColumbo suggested), and spent the rest actually learning how to play chess instead of memorizing lists of moves, they would advance far more rapidly.

Sometimes I feel like people just memorize lines 📖 and don't really play chess. But then I see some games where just 1 bad move in opening ruin everything 😅.
So what you guys think? Is knowing opening theory really that important or just overhyped? 🤔
Knowing Opening theory is very important, but the approach that amateurs take is outright stupid.
Memorizing lines won't do you jack bleep. Your opponents will be low rated as well, and they aren't going to follow those long, deep lines, like 30 moves of Dragon theory. Utterly Useless!
What an amateur should be doing is playing openings that follow, not violate, basic opening principles. Ruy Lopez and QGD are two of them.
And you don't just go saying "I am going to learn the Ruy Lopez with White". No! You need to learn the opening as a whole. The IDEAS (not the moves) for White AND the ideas for Black! You need to be able to explain in basic English, not via chess moves, what White's and Black's basic ideas are. Where are the opposing weaknesses? Where are your strong points? Where should you be attacking? Should you be on attack or defense at any point in the game. If the position is worse for you, you need to grow some level of maturity and realize you are not winning that game and play for the draw.
Just because you can spew lines means nothing. I could tell you the first few moves of many different lines of the Grunfeld, but the overall opening and the game play that follows makes absolutely no sense to me. That varies from person to person based on the way they think. I have played the French as Black for decades. Just because I have mostly played it as Black, probably close to 800 times over the board (LITERALLY), because I actually understand the opening and not just memorized lines, I am fully capable of playing the White side of the French and probably have 50 to 75 times in over the board competition. Not nearly as many as with Black, but I have ZERO fear in playing the White side of the French because I actually understand it, not just memorize it.
The same can be said for me in the QGD, Stonewall and Classical Dutch, KID, Petroff, Closed Sicilian, Ruy Lopez, etc.
At the same time, I am an expert, not a grandmaster. A grandmaster can handle positions from any opening. An expert cannot. A few openings that make absolutely no sense to me at all, and I avoid from both sides like the plague, are the Grunfeld, Modern Benoni, and Alekhine. Especially those lines where one side has the big, mobile (key word - in the Kings Indian, White has a big center, but it is blocked, not mobile) center, like the Flick Knife Attack in the Benoni, Four Pawns Alekhine, and Exchange Grunfeld.
So UNDERSTANDING openings is critical, and you should start with ones that are simpler to understand and don't violate opening principles. Don't make the mistake of thinking that you can master the Najdorf as a 1400 player, or start doing something stupid that violates basic principles, like the Scandinavian, which violates the don't move the Queen too early principles, or the Alekhine or Pirc, which don't fight for the center.

Openings matter a lot.
If you lose a game because you were playing without a plan, and later managed to blunder a whole piece as well because of a trivial tactic you have missed- but still survived because the opponent blundered the piece back, and later you lost an equal ending because you had no idea how to handle it... well, in this case, you may declare "I lost this game because I played a poor opening".
Else, you would have to admit that you have no chess skills, and you are too lazy to fix this issue.
Openings matter a lot.
If you lose a game because you were playing without a plan, and later managed to blunder a whole piece as well because of a trivial tactic you have missed- but still survived because the opponent blundered the piece back, and later you lost an equal ending because you had no idea how to handle it... well, in this case, you may declare "I lost this game because I played a poor opening".
Else, you would have to admit that you have no chess skills, and you are too lazy to fix this issue.
What openings do you play as an IM

Openings matter a lot.
If you lose a game because you were playing without a plan, and later managed to blunder a whole piece as well because of a trivial tactic you have missed- but still survived because the opponent blundered the piece back, and later you lost an equal ending because you had no idea how to handle it... well, in this case, you may declare "I lost this game because I played a poor opening".
Else, you would have to admit that you have no chess skills, and you are too lazy to fix this issue.
Hmm, what do you think about learning opening traps? I don't mean playing them, but learning them so that you know they exist. It seems like they can enhance your imagination and your tactical vision in a way that helps you to understand the philosophy and logic behind certain moves in the opening play?

Two jet engine mechanics walking along a major airport runway---
"Hey Bob, isn't that part of a jet engine?"
"Gee, Stan, looks like it is, metal fatigue, I guess. Looks like it just came off recently, Yikes! It's still hot!""
"Think we ought to say something?"
Naw, Stan. It probably isn't that important."

Openings matter a lot.
If you lose a game because you were playing without a plan, and later managed to blunder a whole piece as well because of a trivial tactic you have missed- but still survived because the opponent blundered the piece back, and later you lost an equal ending because you had no idea how to handle it... well, in this case, you may declare "I lost this game because I played a poor opening".
Else, you would have to admit that you have no chess skills, and you are too lazy to fix this issue.
Hmm, what do you think about learning opening traps? I don't mean playing them, but learning them so that you know they exist. It seems like they can enhance your imagination and your tactical vision in a way that helps you to understand the philosophy and logic behind certain moves in the opening play?
Sure, if you analyse all your rapid+LTC games afterwards (I wouldn't bother about blitz and bullet, they are just for having fun and probably forgetting one thing or two from what you have learnt) you will also have some opening questions, which will be usually met by just the opening principles. But sometimes you will have to deal with such traps.
When I learned how to play, which is more than 55 years ago, I did not bother at all about opening theory. Whatever I have learned about the opening was via studying complete games from the masters. The essential books were Bronstein's Zurich 1953, Reti's Masters of the Chessboard, Fischer's 60 memorable games... and such. Today, the engines are always suggesting the best moves, but since they can't explain in human terms the reasons, the information from them for the new players isn't very useful.

Sure, if you analyse all your rapid+LTC games afterwards (I wouldn't bother about blitz and bullet, they are just for having fun and probably forgetting one thing or two from what you have learnt) you will also have some opening questions, which will be usually met by just the opening principles. But sometimes you will have to deal with such traps.
When I learned how to play, which is more than 55 years ago, I did not bother at all about opening theory. Whatever I have learned about the opening was via studying complete games from the masters. The essential books were Bronstein's Zurich 1953, Reti's Masters of the Chessboard, Fischer's 60 memorable games... and such. Today, the engines are always suggesting the best moves, but since they can't explain in human turns the reasons, the information from them for the new players isn't very useful.
That makes a lot of sense, thank you!
I am trying to improve my tactical vision by playing the open games with 1 e4 (like Scotch openings or King's Gambit) and following the opening principles--develop your pieces, get your king to safety, and fight for the central squares--given by Magnus Carlsen in a youtube lesson.
My question is philosophical: should I play open games with 1 e4 in blitz games and something richer and a bit more strategic/closed (like London or Spanish) in long games? I don't mean for maximizing my winning chances in the game, but for my long-term chess education.

If you can figure the flow as you go then you you can make sense of the opening regardless of book knowledge.

Sure, if you analyse all your rapid+LTC games afterwards (I wouldn't bother about blitz and bullet, they are just for having fun and probably forgetting one thing or two from what you have learnt) you will also have some opening questions, which will be usually met by just the opening principles. But sometimes you will have to deal with such traps.
When I learned how to play, which is more than 55 years ago, I did not bother at all about opening theory. Whatever I have learned about the opening was via studying complete games from the masters. The essential books were Bronstein's Zurich 1953, Reti's Masters of the Chessboard, Fischer's 60 memorable games... and such. Today, the engines are always suggesting the best moves, but since they can't explain in human turns the reasons, the information from them for the new players isn't very useful.
That makes a lot of sense, thank you!
I am trying to improve my tactical vision by playing the open games with 1 e4 (like Scotch openings or King's Gambit) and following the opening principles--develop your pieces, get your king to safety, and fight for the central squares--given by Magnus Carlsen in a youtube lesson.
My question is philosophical: should I play open games with 1 e4 in blitz games and something richer and a bit more strategic/closed (like London or Spanish) in long games? I don't mean for maximizing my winning chances in the game, but for my long-term chess education.
All kinds of openings can result to tactical chaos. Yet, I do think that open positions like the ones from the Scotch or Scotch gambit have more chances to lead at a tactical battle.
IMO the main thing is practicing a lot of puzzles, starting with no timer. You can do it either here, or at "the other place", it doesn't make much of a difference. This will make you to (at least) be alert of many tactical patterns, and hopefully spot them during a game.
And I think that having different openings for blitz and LTC is a bad idea. There are no passive and aggressive openings, it's up to the player to play passively or aggressively. Just learn one opening instead of two, and learn it well.

I use chesstempo but idk if its any good because its just random theme
I dont like "the other place" which I know exactly what you mean, and I dont want to buy a premium on chess.com haha

I wish to win, but more so, I wish to beat you, they aren't the same things. When asked what openings I hate, it seems to be whatever my opponent is playing---Sissycilian-hate it, Queens Gambit-hate it, Crappy-Kan't--hate it; flank opening-hate it. Garbage Opening-hate it, respectable opening-hate it.
on high level. On low levels just intuition
Don't just tease the low rated levels. In chess.com, the year 2022, there were two grandmasters at the elo rating of 456 and 471. It had happened because at first they played as beginners and then didn't use chess.com for 10-12 years.