I don't think it's as rare as you might think. There are several of us here who didn't use a formal program and have managed to stop drinking and live a quality life for years. As I said in your other thread, I don't think it's fair to say your father isn't serious about recovery just because he doesn't use AA. Everyone is different and while programs like AA have helped many, many people, that doesn't mean that anyone who stops on their own will ultimately fail.