Do you have any horror stories about problem players or DMs being unfair?
I'm playing a DND homebrew game where we're all villains. Sneaking around and stealing stuff, no qualms about killing innocent civilians, etc. Except there's one player who is borderline refusing to work with the party, including attacking other players for no reason. I get that we're playing evil characters, but surely the least you could do is work together with your fellow PCs. Evil doesn't mean "I hate everybody", right? It's a frustrating experience, and I just feel bad for our DM who is new to DMing and doesn't want to disappoint their friends.
I would only ever run an "All-Evil Campaign" if all your players are very good and you trust them and/or you have some rules and guidelines to keep them focused. There is an excellent 3rd party Pathfinder adventure path called Way of the Wicked that pulls off the "All-Evil Campaign" really well. The party must be Lawful Evil, right from the get go the plot establishes a great reason why the party should be working together, and a diabolic contract makes sure they wont try any funny business with their boss.
Even though you're not the DM, it still doesnt mean you cant talk to other players one-on-one and discuss their actions with them. They're your friend (hopefully) so just bring up what problems you have and try to sort it out
I have not considered that, I think I'll bring it up with my DM... it's my first "all-evil campaign" so I just figured we'd be good to play without putting some guidelines in place! I've talked to the DM before about the player but I think next session I'll talk to the player in private, tell them cooperation is key. They have a lot more experience with regular RP than tabletop which is probably where these issues are coming from.