Forbidding drugs is insulting to human agency and is probably one of the reasons it doesn't work very well. If someone wants to destroy themselves (referring to the nasty stuff here) it should be their right. It's a medical problem if people are sick. A healthy person should want to maximize their potential and not want to play with fire and risk it all.
It's just that the tragic figure is somewhat romanticized. I know all about the romanticization of my condition, and I just hope to profit from it, but as I just stated that's healthy behavior. Nonetheless I still think that this tragic figure thing we have is perhaps not the greatest contribution to art and therefor people's psychological makeup when it comes to self destructive behavior. Mind you, there are many other reasons people risk their lives and do dangerous things.