Bernie Sanders is an account that is the head of a whale group that does, in fact, go around and downvote posts. He's the vigilante that naturally arises in every system that has poor rules to prevent bad actors from abusing the system. Unfortunately, vigilantes are themselves not a good system, either, and will result in more vigilantes to oppose them, hence his negative reputation.
RE: @sweetsssj is the largest abuser of last minute upvotes!