Doing drugs is an inherently morally neutral thing to do. it has no value one way or the other. It is simply how one chooses to treat their own body, and as one's body is literally the one and only thing on this planet that a person owns, I feel it is the individual's right to decide how they treat what they were born with. That includes shooting themselves in the head if they want. If some people do drugs in moderation, it'll simply be an enjoyable activity that some people do and then move on. I know many people who are fully functioning members of society who dabble every other week in this or that, and their life is completely unaffected (and statistics suggest this is actually the norm rather than the exception).
Doing drugs does not necessarily lead to 'misery.' It leads to misery for some people, but so does skydiving or bungie jumping or base jumping (percentage wise, more people die from base jumping than any drug on the market). Are we going to say the makers of the equipment these individuals use are profiting from misery? These people are in a pursuit of a high scientists of all kind admit is equivalent to drug use. And it's similarly dangerous.
I respect those that disagree with this view, but I doubt I could ever understand it. If you really want to give up your right to do whatever you want to your body, that's up to you. I, however, came into this world owning my body, and I owned this body in every action I commit in this life, and I hope to die on terms I am happy with. If that means my heart explodes because I made a bad choice, that's my bad choice to make. There's nothing morally wrong about such an act.