But if you want some of the nasty shit, you usually know what you're about to get into. Not because school, teachers, priests or other fairy tale godmothers tell you about it. Because you effin' SEE what it does. Few people push their first time themselves. Most have some "help". From people who have been doing it for a while.
Or you mail order it from the Silk Road of the day. You keep on pushing the "dangerous drugs are used by desperate people" angle, but they're also used by people who simply want a thrill. And the fact is, at this point it's next to impossible to know how dangerous any particular substance really is. There's too much misinformation around. So people say "screw this", throw caution to the wind and do it.
And of course that's how it works with everything else, too. How many people still care about nutritional recommendations, which get revised every few years, rather than simply eating what they want?
Just take a moment to ponder how fucked up your life has to be that you consider a slow, agonizing death with a brief, occasional high a pleasant alternative.
And this is another thing: a typical drug-related death is not slow and agonizing, it's overdoze. Tobacco is the only exception I can think of, yet people who's lives are otherwise just fine smoke anyway.