IB, I agree with both Snodderly and Antonia. A lot of this is about feeling OK with himself and his choices.
I really believe that very deep down they know they have wrecked their lives, but they are surviving, not flourishing, and that is OK with them.
For some of them their world caves in eventually, but so many just go on existing and they have this overwhelming need to believe it could not have been otherwise. That is a crucial for them, I think. Otherwise where do you go from here? It is either clean up your act, or go on as you are, trying to convince yourself you would have ended up there anyway.
