It's entirely reasonable to discuss the extent to which drugs themselves contribute to social problems, but by this point, I think it's reliably evident that drug prohibition doesn't effectively address any social problems that might be attributed to drug use. Indeed, it's become clear that the social problems caused by prohibition are themselves more pervasive and more destructive than those caused by drugs themselves.

But it's still wrong to assume that drug use is inherently a social problem: there are plenty of people who can and do use drugs moderately, while still remaining peaceful and productive members of society, and these people are victims only of prohibition, not of the drugs themselves.

We should be careful about what we recognize as contributing factors to social problems at the macro level, especially where those influences affect the macro-level society only by way of willful human behavior. Everything might be rightly construed as a potential influence on human behavior, and anything taken to excess might inspire dangerous or irresponsible behavior; but it's very dangerous to treat human beings as fungible stimulus-response machines, and locate the nexus of responsibility for outcomes in the complex of external behavioral influences rather than in human agency itself. People should be held accountable for the actual, quantifiable harm they do to others, with consideration of what external influences contributed to their actions having only a role to play in deciding how to respond to people who actually are harming others.