hi chess is so fun
Why are 1200s so good

Detach yourself mentally from your or your opponent's "rating".
If all you're doing is playing for a rating, it becomes a serious grind and won't be fun anymore.
This line of thinking is why so many young men in particular - struggle with life.
You have to know where you rank in any situation, know what you have to do to move up, and work relentlessly to attain that move upwards.
You need to be honest with yourself about where you rank, and ELO tells you that you are not good, well, you are not good. Identify what needs to be done to improve, one thing at a time, and see that measurement improve.
Thats not just chess, its life.
You're right when it comes to training. Knowing your level and your weaknesses is key, for all sorts of reasons. But it's not just about rating. Some people are simply good at performing under pressure, while others—who aren’t any less skilled or knowledgeable struggle to show it. Traits like stubbornness in calculation are insanely useful and something you need to bring to a solid level.
Choosing the right resources and topics really depends on your actual playing strength.
That being said, Elo is just a summary of past results. In single games, it hardly matters. I don’t even want to know how many times I got into worse positions just because I underestimated someone based on their rating. The thing might also work exactly the other way around and one might overestimate the opponent.
In my first game against a GM everything he played made sense to me, because I was assuming that a GM must play very strongly. After he took half an hour for a move I realized that it was me who had outplayed him - despite a 750-rating difference (I still went on to mess up badly and lose).
From outside it always looks strange when my students are underestimating or overestimating an opponent, but I made this experience and so has everyone else.

Just bcuz they are better than 1200s, I'm 1000s and my opponent's game rating usually 1700s or higher, and some of them used to be 1500s but they lost their elo for some reasons

the same tip:
1. Find openings that you like and understand
2. Get more experience by playing more games, it's the key
3. Find and use your strenghts, for example i try to play only in good mood
im 1300 now sui but i bet I'm gonna go back down pretty soon
GUESS WHAT I WENT BACK DOWN I WANNA JUMP OFF A BRIDGEEEEEE(IM KIDDING DONT TAKE THIS COMMENT DOWN) HOW AM I GONNA REACH 1500 AHAHAHAHA
Crashing out

In the past, players around the 1200 level mostly reached that rating by memorizing simple openings like the Italian Game. Nowadays, however, 1200-level players often study and memorize more complex variations similar to 1400-rated players. This makes the games at the 1200 level stronger and more challenging than before. The widespread availability of online platforms and training resources has greatly contributed to this improvement.

I'm 1200 Rapid and can attest to playing only when rested and sharp.
Lotta mistakes come from mindset, I dropped 300 points in Blitz because I repeatedly played while very stressed and impatient. I should be an 800-1000 Blitz but in the 400s as of now, looking at my results over the last week, ugh.
And that was playing at night when couldn't sleep but was tired, etc. lot on the mind. I got frustrated but wouldn;t stop.
Take a step back and look at where you missed opportunities. Then play refreshed.
Because there are loads of very experienced players that fill the lower ranks. This devalues the elo and thus your 800 is actually a 1000 and your 1200 a 1400, and so on.....
ok