I don't believe there is much of a choice in the matter, really. I've never used heroin in my life, but if I had I don't think I would have become psychologically addicted to (physical withdrawal is harsh, but doable, the physical addiction is not what makes people go back to the drug). So junkies are ill, yes, but not because they take heroin, they were already ill well before (and in 9 out of 10 cases: with multiple previous and concurrent addictions). That's not condoning heroin, it's just that the disease is deeper than the drug.
This from a totally non-addictive person whose demons lie elsewhere: compulsive completionism!!! Not bad for your health though. ; - )