As I understand the mission of this site, we participate in order to help one another recover from the effects of addiction in our lives, however that may be manifested. Therefore, my response to your post is to gently urge you to disengage from your current path of trying to prevent your friend from experiencing the reality of his addiction. It is harmful to you both to do so.
You are not responsible for him, nor can you save him – that's entirely up to your friend. If he has people threatening him harm, then he should seek help from the police or other authority. If you are thinking, "But then he'd have to explain how he got the money to begin with" my response would be, "Yes, and so…?"
There are consequences to the choices we make in our lives, not only for people addicted to substances, but to those who love them. One of the keys to our recovery is acceptance of reality, which implicates living honestly.
I don't mean to cast a shadow on your affection for your friend -- it's great that you care for him. But this is not your responsibility, and if you choose to make it so, you are opening yourself up to a world of pain. Many of us here have lived in that world and we work hard on ourselves in order to never, ever return.