People abuse drugs largely because they're not happy, they're not getting any enjoyment out of life. Maybe they can't afford enjoyment, maybe their particular brand of enjoyment is illegal, perhaps their brand of enjoyment is taboo, but for whatever reasons they're not happy. Drugs provide a burst of enjoyment filling a terribly important need, the lack of enjoyment is akin to the lack of food, starvation.
Today we punish a person for not being able to find happiness by throwing them in jail and/or rehab. In such places they are deprived of their friends, their family, and the things they enjoy. Today in order to solve the drug abuse problem we take away a persons happiness which is exactly what caused the abuse problem in the first place. We're only making the problem worse.
I believe people need to be free to find whatever it is that makes them happy. Free from laws cooked up out of thin air and free from the judgment of their peers. If a person is not starved then they will have no need to turn to artificial sources of pleasure. Even then I believe that the use of many substances currently labeled as illicit will continue, but the abuse of such substances will cease.
The abuse of drugs does not mean a person is broken, it is an indicator that the system is broken. The system produces unhappy depressed people, it is of no surprise that anti-depressants are among the most commonly sold and abused drugs. The solution to the problem is not war, it is a major overhaul of our way of life.