If we take opium and Heroin for example Heroin abuse was not ramped until the availability of opium and laudanum where no longer available. Opium, despite the fear mongering, is a relatively safe product with few deaths attributed to it, it was also the drug of choice among opiate abusers until it's abolishment at which point Heroin became the primary substance of choice due to availability. The same can be applied to the coca leaf and crack.
We should legalize the natural forms of these drugs and we will see the market for the expensive hard stuff dry up.