If you’re in a group (real life, online, wherever) then you are expected to conform to the rules of the group. Cross a boundary, or even just push its limits, and the reaction can be varied, and sometimes quite unexpected. It doesn’t matter who was objectively right or wrong (if there is such a thing in play), what matters is the rules of the group.
The rules of the group can help sweep an individual into a world of things they aren’t comfortable with. If everyone gets pissed every Saturday and you don’t, that is likely to slide. It’s non-participation, and that’s a little easier to forgive. But try saying that maybe it’s not healthy to live a life so soaked in alcohol, and you’re ripe for ejection. It’s part of being in the group, and questioning it marks you out as ‘not like us’.
It makes it hard to stand up to a group of people you know, who are your friends, and say something unpopular. It takes a lot of guts to hear people joking about bashing someone and stand up and say ‘no, that’s not ok’. It’s hard to watch someone make jokes about sexual assault and call them out on it. Maybe, if you’re lucky, they will look at themselves and think ‘no, I don’t want to be that guy’, or maybe the blame for disrupting a sick joke will blow back on you.
It’s hard being the one who stands up and says no, but it says a lot about your character.