I think there's something in drug use that many fail to recognize because of the way society paints it. Namely, we as a social species consume drugs socially. Everything from sex, to alcohol to cigarettes. If it isn't done socially, I know for a fact that the act generally incurs guilt and self-loathing. If it is done irresponsibly in that group, it ALSO incurs guilt and self-loathing.
In this way, drug use mediates itself. We have a bunch of fuck-ups who seem to think that drug use is loathsome because the only experience or understanding they have of it is a kind that we are biologically wired to dislike and disdain in ourselves and others.
There won't be a health crisis from legalizing drugs. It may even resolve the health crisis that has been simmering since prohibition started, because drug use in humans doesn't work the way people in America seem to think it does.
The one exception to this seems to be 'utility drugs' and opiates. The first class being drugs you take in order to utilize the effect for productivity: caffine, cocaine, amphetamine. And the other because it lets you feel good when you specifically disengage from society. Utility drugs, you get tolerance and dependence, and then the drug ends up sending you out of balance. I've been trying to quit caffine for months now, and it's ROUGH. I can't imagine how much worse more powerful stimulants would be, but thankfully I don't use stimulants except in SHORT bursts. Maybe a day or two and then stop.