This is like the chicken and the egg... addicts are selfish, selfish people can become addicts, not all are. Have you seen the movie "trainspotting"? there's an excellent scene where one of the characters, Mark Renton, will not let a girl who just lost her baby take a hit before he does. How's that for selfish?
Without having much information sounds like his parents had lose boundaries and he never really felt the consequences of his actions. His parents probably enabled him more than they would admit.