As a former alcohol abuser, I say, legalise drugs. I found it hard enough to give up booze with it being cheap and legal. It would have been impossible if I had been socially marginalised by it also being illegal....
The way I see it, I feel sorry for addicts, but also hold them responsible for their behaviour. If they mug a little old lady, that is downright shitty, whether for drug money or not. But I support treatment instead of incarceration as jail is NOT a drug free environment... I know a prison nurse, he assures me of this.