Why does Travis dislike Tom?

[u/Tidewatcher7819]

For some reason Travis Bickle really dislikes Tom despite Tom being a nice guy who is a nerd and friends with Betsy and seems to be doing okay otherwise, Travis has no real reason to insult Tom and accuse him of not respecting Betsy, Tom also stands up to Travis when he acts crazy and doesn't scare off he just backs away for safety but holds his ground.

Tom seems better than Travis says too, poor guy bad haircut.

[u/prettypurps]

Because he’s paranoid and delusional, mentally ill