In general, it's a load of bollocks. Obviously there will be some exceptions, if you have a crazy theory there's bound to be /someone/ who believes it with all their heart, but for the most part no, not at all. Nice people are nice, and I'd much rather hang around with a bunch of people who are nice than a bunch of people who are assholes and cut themselves on how edgy they are.
There does, however, need to be a distinction made between people who are genuinely nice people (good!) and people who pretend to be nice to get what they want and then get angry when everything doesn't go their way all the time (bad!). Being passive aggressive and clingy isn't actually being nice, it's just kinda creepy and slimy. The whole 'nice guys finish last' idea is mostly pushed by the second group of people, trying to justify why nobody actually likes having them around.
As other people have said, you should never look to entertainment to get a legitimate picture of how actual people think or behave.