Cognitive Dissonance. I know quite a few people who became evil…went to the Dark Side. None of them them thought they were doing anything wrong. What happened was once they got themselves into tough situation (either because of something they did, or bad luck), they had a choice. Admit it and deal with it, or take the easy way out and blame others, or make it about them proving that they would prevail no matter the cost. They chose the latter. They will never, ever see it any other way. They will destroy their lives and even their children in order to avoid facing the pain of reality. And the longer they wait, the harder it is to jump off the rising balloon of delusion.