Alcohol has a much more detrimental effect and still is completely legal (also: any attempt of banning it had quite bad results). So yes, some people don't handle it wisely. Lets not even get started on tobacco. Or all the other substances, which are not drugs but very bad for your health when overconsumed. Like all the sugars, unhealthy fats. Fast food.

We cannot and should not penaltize all these things just because a few cannot handle them. Rather, we should invest into helping and preventing abuse. Of all above.