I am a recovering cocaine addict myself. I am 22 now and began at 17 in college. Peer pressure is a hell of a thing, trying to fit in and be accepted. I used cocaine as my crutch. He has to really in his heart know that he doesn't want that life again and remember all the bad things that happened because of the drug use. We addicts have a habit of only remembering the good drug related experiences. Once he is willing to stop at all costs he will do very well. Carry him to some NA meetings which are anonymous and he can hear from other addicts as well.