Gaming

The gist is... streamers are gamer role models. The streamer itself is a drop in the bucket... but either they encourage people that like their behavior to play the game, or they encourage people who play the game to act like them.

I used to play town of salem, the social deduction game... the community was relatively small, but when a mainstream youtube channel like pewdiepie or someoen played the game there'd be a collective groan from the community. As it would always follow up with a huge spike if players who start up the game with zero interest in learning how to play (because the youtuber also didn't learn how to play)... now in those cases that generally was only a week or 2 of annoyance as the obnoxious players either moved on to the next thing, or started actually trying to learn the game instead of just trolling everyone.

Toxic behavior being normalized leads to other people acting similarly.

I mean, "haha screaming so funny, I do same thing cause I want to be funny"