If theres going to be a party then the players are responsible for coming up with a justification why their character would agree to work together with the rest of the party. I will always welcome even evil characters if and only if their player can actually show that they are capable of the necessary teamwork. The evil guy helping good guys begrudginly because they get something out of it is a classic trope and that’s all fine.

Meanwhile, if your alignment is the classic Chaotic Stupid and you go full murderhobo and backstabber, why would the rest of the part ever tolerate that? They’ll turn up face downwards in the nearest ditch and the player can try coming up with a new character that actually wants to be in the party.