I like to think that it's human nature to be self-preserving, on some level besides physical, and that we are to be blamed by our own moral systems when that nature takes us into whatever bounds we consider to be evil. It's the idea of a self-optimistic person that because it's circumstance that led them to a state like this, that their behavior is excused and shouldn't be met with any sort of judgement, or that because they are like this that it isn't their fault (fault being a synonym for imperfection) that they're like this, etc. That's not really my reason to ctb or anything, but I've fallen so low that I've come to understand that I'm just not a very good person, and that at the end of the day, a lot of the blame is objectiely on me.