I think it has to do with the morals or lack of morals he lives by. To him human life is nothing more than a joke. So he is able to live out any fantasy without remorse and takes pride in doing so. It's like he has taken the throttle limiter off his self.
Maybe I have just been playing to much Twisted Metal. And I am constantly falling in love with something than switching to something else next week.
Just look at that face it conjures the reckless, evil and sadistic side of me. I can't help it. I think we all have those slightly psychopathic sides of our personality. Though they are just usually held in check.