The only drug I have experience with is alcohol so I'd say that apart from soft drugs (alcohol, marijuana, etc), habitual drug use is irrational and generally not a good thing. However if you take mushrooms like once a year I'm sure you won't die and I can see what people get out of that.
I'd also like to add that as for the legality of drugs, I think every drug should be 100% legal for three basic reasons:
a) The government should never be able to encroach on your body rights unless it is absolutely necessary (if for instance there's a bullet inside of you that would implicate you in a murder, then the government should have the right to take it out to analyze it, but the government can't prevent you from smoking a cigarette or eating bacon or cutting yourself if you're emo)
b) legalizing drugs means that they become government-regulated, taking profits out of the hands of criminal organizations and making drugs healthier on the whole. I think there might be a marginal increase in the rate of drug use but nothing huge, since I think if anyone really wanted to do heroin, they would do it whether it was legal or not (I know it seems counterintuitive, but think: have any of you actually wanted to do heroin? There are lots of barriers, like the fact that it's absurdly unhealthy, keeping people from ever wanting to do that)
c) when drugs are legal, drug-users are treated as people suffering from an illness, and not as criminals, so they can actually seek help for their addictions.
Again, I may think that drugs aren't right for me, but that doesn't mean I should be allowed to decide whether they're right for everybody. Plenty of productive, intelligent people do drugs so it isn't a universally bad thing. I just don't like it myself.