You're right, though, crack and some others seem to have horrific addiction profiles and I've even heard of Brazilian drug-lords forbidding its sale in their territory because it destroys any sort of community stability and kills the market.
I do wonder if many people would bother getting started with crack if other drugs were open to them. I also think that if there wasn't the criminal stigma we could help more of them, sooner.
There's no perfect solution, but what we have isn't working.