About evil PCs killing villagers because its fun:

Sure, powerful warriors should be able to wipe out pretty much anyone living in a small village. But that village is part of a kingdom that has an army, bounty hunters, hired wizards, etc. If they kill the bounty hunters, better bounty hunters get sent. If they kill enough bounty hunters they have paladins coming after them. If they kill enough paladins there'll be an army coming after them with spellcaster support. If they kill the army of that kingdom, other nations send a joint force. If that massive force is killed off various archmages and epic level clerics from around the world come to stop the growing threat. Unless your party wants to fight everyone in the world they have to play evil smart.

Evil Smart is like the mafia. They operate ruthlessly and secretively, kill opponents, bribe politicians, threaten innocents, amass fortunes, but they don't just kill on a whim. I suppose your characters could be roving serial killers but serial killers don't amass fortunes.