You have to have a neuroses of some kind to push yourself to the extent of these people.
If you are a well adjusted, content person you won't push yourself like them. In other words, if you feel good about yourself, why would you take harmful drugs to change yourself?
Bodybuilders are an insecure lot, usually have self-image issues of some kind, dislike themselves.
Poster boy for this would be Rich Piana.
Arnold - father issues, insecurity
Ronnie - mental case, hard background
Dorian - hardscrabble background, father died when he was young.
Ferrigno - deafness, insecurity, father issues
Danny Padilla - shortness, insecurity
Etc.