Not a book so it may not count but Warren from Buffy springs to mind.
Here's a kid who can do whatever he wants. Super intelligent, good at making machines he could get a well paid job and make a fortune with an honest living (seriously, the government would pay millions for some of his inventions)
Yet, he decides to use his abilities for crime, to take the easy option to riches. Plus, over the course of Series Six he slowly becomes more and more evil, sending a demon to kill Buffy, trying to kill Buffy with the invisibility ray, planning to frame Jonathan, murdering his ex-girlfriend and framing Buffy for it and eventually, shooting Buffy and Tara.
All the while he shows no regret over any of his actions and only cares about himself.
He's an awesome character and his evilness is all because of his own selfish actions. He wasn't born evil like some characters, isn't a demon, didn't have a particularly bad upbringing etc and doesn't really have any redeeming qualities at all.