Society's approval or disapproval is the cause of laws, not the result of them. If people, especially teens, believe an activity is harmless, we cannot convince them it is harmful simply by passing laws against it. Prohibitionist's Argument De-criminalizing drugs would cause an increase in the crime rate. Violence of the drug trade occurs because drug dealers are drug users Reformer's Argument De-criminalizing drugs would cause a decrease in the crime rate. Alcohol is the only significant exception.
Teenagers buy drugs from despicable adults who prey on children.
We should consider harsh punishment, up to and including executions, to discourage these adults from corrupting our youth. If they sold legal products, like whiskey or morphine, they would be very careful to make sure their customers met legal requirements. Typical drug dealers are young children, especially in the inner cities. If we executed all drug dealers we would kill a lot of kids not yet in their teens. Prohibitionist's Argument De-criminalizing drugs would increase their availability to children.