Many Comedians are simply.. fake assholes on a stage?

Okay, I’m not gonna claim all comedians are assholes the point I’m trying to make is, but many act like they are on stage, and suddenly it’s funny. They complain about this and that, give example replys to example situations that would fit an asshole perfectly. If you meet one in real life, the natural reaction is to tell him/her get lost or even ignore him/her. But put them on a stage, BAM! It’s funny, what’s up with that? How is it funny? I don’t get it..