Being an edgelord, playing an antisocial character or “evil” characters in general

We're all here to play a game and have fun. For most it's not fun to have someone else in the party who is causing problems with their edginess or going around stealing from the other party members or doing things to cause harm to the group. (I'll admit it's not fun for DMs, either.)

I know you're supposed to roleplay, but players having to watch their characters' backs against the world while also worrying about other PCs or suffer the consequences of someone who is random for no purpose but their own edification is just… exhausting. It's also not fun. At the table, let's agree that the party are all allies and we hunt the monsters, not be the monsters.