Hi nightmare, hope you keep coming back here, there's alot of support here if you need it.
As far as him hitting his bottom, he won't hit it if people keep helping him. You say that you know you can't help him, but you are... by giving him a place to drink, do drugs, and pass out every night. The longer he can depend on/use others to take care of him, nothing needs to change in his eyes. Only when they experience the true consequences for their decisions do they hit bottom.
Just my opinion. How is this affecting you? Have you hit Your bottom?