Ooh, we've got a live one here! Is this the first troll on the new board? From the sounds of it, it looks like one of the more desperate ones.
I'm not even going to bother with the whole "shut the hell up and be a parent" schtick. If he's doing all of those things repeatedly, you failed at that.
Send him to school.. at that point, why even bother? You can force him to go to school if you really want to but you can't make him learn anything. He probably won't graduate (in comparison, a TBS "graduation" means nothing except embarrassment) and his college chances are absolutely nil. There's no reason for him to stay and no reason to continue the charade; you might as well just pull him out.
If he's that determined to fuck himself up on drugs he WILL fuck himself up. If he's killing himself, a few run-ins with the cops will probably snap him out of it. You do know that the most popular thread on the Straight board here is the "I just smoked a huge bowl of pot" thread, don't you?
If he doesn't want to stay home, why make him? He's telling you loud and clear that he doesn't really need you anymore. Stop giving him money. (That last one can put an end to the drugs fairly fast, actually) Make it clear that any crimes against you will be met with, yes, cops. Give him food and shelter as, yes, required by law. You can still do that, right?
Bottom line: If he doesn't want to be your kid anymore, don't make him.
And then formally you let him go, as early as possible, and let him go grow up.
And if he ever comes back to you years later realizing how stupid he was and all the mistakes he made, you use all the money you saved by not sending him to some hellhole to send him to community college.