You have to think "cost-benefit" here. We gamble with our lives, all the time, in a variety of ways. "I only smoke a pack a day, where's the harm?" "One more drink, I should still be right to drive." "I'm only going 500 metres, what's the point of a seatbelt?" etc. We use all kinds of tricks, including substances, to make ourselves feel "normal" — whatever the hell that is supposed to mean. Why should anyone should be prevented from seeking whatever treatment they feel is appropriate? Humans commit all manner of stupidities in full knowledge of adverse consequences (legal penalties, premature death, disapproval from neighbours, etc.) If we are to fall into error, let it be on the side of permitting, not restraining, the act — especially where harm to third parties is not demonstrated.