Part of the purpose of legislation is to reinforce existing social stigmas. Example: incest. Your average person probably isn’t seriously considering dating their cousin, and it isn’t primarily because it is against the law, but because of the stigma attached to it apart from the existing law. The law only reinforces the stigma and acts as a deterrent, and ultimately inflicts a consequence if the stigma is ignored.
I think the same applies to drugs. Most people are responsible adults and would not put their well-being in jeopardy for the sake of a temporary high. For them the, “That’s a stupid waste of time” social stigma is enough to restrain them, but given the right circumstances, like some life changing event that causes depression, the social stigma alone may not be adequate to deter them from experimenting. This is where the law works to deter and ultimately punish.
