There will always be people behaving badly. Maybe that is revenge downvotes. Maybe it is trading upvotes (which feels fine to the people doing it of course, but cheats everyone else out of whatever part of the pool is going to pay for traded votes that don't reflect merit).

It isn't those misbehaving who define the system, it is what everyone else does about it. When you see revenge downvotes, upvote. When you see vote trading or undeserved/bought/self upvotes, downvote.