I understand your point, and it's a legitimate one. But drug abuse harms more people than the drug-user himself. Drug abuse takes a toll on everyone the user comes in contact with. The severity of the damage depends on proximity to the user. The user's immediate family suffers most, and the effect radiates outwards. Do you know any drug abusers? They can cause a tremendous amuont of damage to other people.
Still, I would consider legalization if drugs were taxed heavily, and revenues were poured into treatment programs. Families would also have to be allowed to force drug abusing family members into either confinement or treatment.
You made some good point and I agree with some of them.