why some players don't allow rematch?

I play many games on my phone on the go, and many times I have to put my phone away and don't have time for a rematch.
Personally I don't feel entitled to a rematch, and if I lost a game then that's on me and a rematch won't change the outcome.

It is the player's decision to decide whether to continue or not. If you were insulted in the chat regarding the game, then disable it.

Please note that I make abstraction of unpolite players. When two fair players are opposed, there is respect between them, which should allow for rematch. The fact that some consider "insults" or "bad words" tells a lot on the general feeling regarding kiddos (to stay polite) misbehaving. This damages the respect for your opponent and the respect for chess as a whole.

More embarrassing to lose twice than win twice. Fair players give another chance. If 2:0 okay, if 1:1 tie breaker is exciting 👍
This topic has been done to death, dozens of times. Some players like to have rematches, some players don't. It's as simple as that! There is nothing in the rules or norms of chess that implies that you owe your opponent a second game. If you would like a rematch, ask for one. If your opponent also feels like a rematch, he'll agree. Otherwise. no rematch.

Please note that I make abstraction of unpolite players. When two fair players are opposed, there is respect between them, which should allow for rematch. The fact that some consider "insults" or "bad words" tells a lot on the general feeling regarding kiddos (to stay polite) misbehaving. This damages the respect for your opponent and the respect for chess as a whole.
It is not impolite (unpolite is not a word) to refuse a rematch. When I put in for a game, say 3 0, and the game starts, I am under contract to play ONE chess game. ONE! NOT TWO! ONE! Don't like the fact that you are not offered a rematch after getting your butt hurt, that's your problem!
Maybe Tic Tac Toe is more up your alley. An easier game. If X goes in the middle, go in a corner. If X does not go in the middle, take the center box. Easy to remember! There are other scenarios that draw, like if X does not in the middle or a corner, then you can draw going into one of the two adjacent corners, but why even try to figure that out? If X starts in a corner, you MUST take the center box or you lose!

Sir, unpolite means not polite and is in the dictionary. I am not a native English speaker... Impolite has a slightly different meaning. Well, different people are different opinions. People, including me, write lapalissades. Thank you.

I rarely do rematches. As long as the other player doesn't hold a grudge then it would be OK. But I wonder about the frustration factor sometimes.

For me, chess game is not something personal against an opponent. I feel no need to ask for a rematch when I lose; and when I win and the opponent asks for it, sometimes I grant it sometimes I don't, it depends if I still have the time and the desire to play.
Anyway, there is no regulatory, ethical or fair-play obligation for a rematch, and no one can force others to continue playing. It is a concept clearly expressed in the FAQs of this platform ( see support.chess.com, section "Sportsmanship" )

Some players just get tired of being asked for a rematch. Others just get tired of threads about why their rematch was rejected.

The reason I never do rematches because one person I played with completely messed me up.
This person I played with was a very bad player first game, and then he asked for a rematch, then for some odd reason he started playing better than Ian Nepomniatchi for God's sake. I asked for another rematch, he still checkmated me. He was also keep screaming "mAtE iN oNe". He said he watched a TikTok to learn.

I usually don't accept or offer rematches, win or lose. I'd just rather play different people, and not play the same person again.
Your opponent owes you nothing. It isn't unfair play to decline a rematch.

You never know in which circumstances your opponent plays. Maybe he/she had 3-5 minutes only and should rush somewhere (waiting line in the bank, lunch break finished, kid asked for attention etc-etc….).

Yeah normally I don’t like playing many games in one day or playing them back to back, and if it was a close match that I might’ve only lost by a blunder, and I know my opponent is superior, then I don’t want to lose the points I just got

I don't understand opponents who insist on rematches. Most (all?) chess teachers/coaches say to analyze after a game. I don't know of any who recommend avoiding analysis and playing a continuous stream of back-to-back games.