I've met a few people on TVTropes who claim to be playing a villain role or something roughly cognate to one in real life, without having any particular higher-level reason for doing so in mind; the infamous Troper Tales pages are a particularly fruitful source of examples, although it's likely that a lot of the more extreme ones come out of attempts at trolling.

Even if we discount active attempts at deception, that site selects for people who spend a lot of time thinking about character types, and additionally has the right demographics for many of them to put an excessively high priority on looking cool; it's wise to take this sort of character identification with several grains of salt. As best I can tell the motivations involved aren't usually all that villainous relative to most external observers, but it's self-image that's at issue here.