In general, castling is good. However, as with most things in chess, it depends on the specific game and position. If the center is locked up and not likely to be opened, delaying or forgoing castling may be a valid option.
Is castling a bad move?

At the club level, I've noticed some respectable players, not masters but competent duffers, who never seem to castle.
There isn't any chance that there is any truth in that statement.
From my experience the type of player you describe is one who plays some sort of hypermodern system where they wait with committing their king for as long as possible. While the moment you castle they quickly start throwing the pawns towards your king. Then in the case you try to blast open the center only then they will castle on the opposite side. While if you try to attack on the opposite wing right away the king will likely stay in the center.
This seems to make sense. With these guys, you get lots of double fianchettoes. No pawns past the third rank until you have castled, etc. I am not really good enough to understand what they are trying to do. This sheds some light. Thanks.
honestly, checkmates are more easy to figure out when my opponents castles. It also depends on where the rook is placed. I honestly don't know how to get the rook to be placed outside the pawns(like next to it but still in the bottom). Whener I castle, the rook is always placed straight on bottom of the pawn which is least favorable

Castling is kinda bad in my opinion because it can lead to an easy checkmate. In most games where my opponent castled, I easily checkmate them. Though if they know and defend the piece that would lead to checkmate, I attack the piece, and they blunder. I don't castle because of the fact that checkmate plans can be easily formulated causing me to defend myself.

Blindly castling is as effective as making any move blindly. You need to work out why you might want to castle. Also, if you've worked out how to attack a castled king, then you've pretty much worked out how to defend one too.
Castling is a very powerful move. It is like 3 moves Kf2, Rf1, Kg1 for one, so it gains 2 tempi.
It brings the king to safety and connects the rooks to activate them.
#11
"Before the endgame, the Gods have placed the middle game." - Tarrasch
In the middle game the king must be safe on the g-file and the rooks (the most powerful fighting units after the queen, and together more powerful than the queen) must be connected and activated.

castling is a bad move because you move the king away from the center and in the endgame you have to lead the king 2-3 more moves to your pawns which can lose the game
Says the player with a 100 ELO rating and 29 wins and 221 losses.

There are people with greater expertise than me responding to this thread but if I haven't castled by the time the end game begins then I probably won't do it. As has already been hinted, it is a move which is usually most effective in the mid game.
At the master and GM level, of course it isn't. At the club level, I've noticed some respectable players, not masters but competent duffers, who never seem to castle. They also play the weirdest openings but that is another thread. Is there some plan behind it or do they just not get around to it?