Well I'm not on the inside to have the answer to that. But if you want reasons why that wouldn't happen. They may have their own problems (drugs or other) or are simply enabling him not realizing the extent of the problem. You also forget that he is supporting them, if he wasn't lying about that. Which brings in the golden rule. He who has the gold makes the rules. He could also just say if I have to go to rehab I have to pause and then you can't pay your bills. There are a bunch of reason why they wouldn't or couldn't step in. I don't know the people he has around him. But addicts are usually surrounded with enablers and other addicts.
Look I don't know BD at all. Feel free to chalk this up as someone's random speculation. Though I'd bet real money right now that he'd fail a drug test today, and I don't mean for marijuana. There are simply to many signs for me to think I'm wrong. Hopefully I am because I wouldn't wish that on anyone. Even BD.
Probably