An intelligent, wealthy, employable person can dabble with them, have a good time, and usually get away with it. Should they get addicted and screw up their lives, they can usually get help and bounce back without permanent consequences.
People who're a little less well-off intellectually and economically aren't so resilient. Should they get addicted to hard drugs and screw up their lives, they usually don't bounce back from it - their lives are ruined forever.
Since HN is full of intelligent, wealthy, employable people, the comments on this thread don't surprise me a bit. And yes, I agree that drug policy in the United States could stand to be reformed a little. But when evaluating the harm a person's actions can cause to society, I wish people would think a little more about not just themselves, but that vast chunk of society that's not lucky enough to not be as privileged as we are.
Remember that the first step of the twelve steps is "admitting that one cannot control one's alcoholism, addiction or compulsion". Finding reasons why you are more privileged than others makes this step even harder.