Seems to me that what today's Europe proves is that relying on the government to solve social problems simply doesn't work. The War on Alcohol was fought almost a century ago in the US and showed clearly the gangsterism which results from outlawing a substance that people want.
Unfortunately, the present War on Some Drugs is being fought without the benefit of a Constitutional Amendment to permit it. As a result, there is no amendment to repeal in order to stop the madness.
"A substance that people want" being the key phrase. Two-thirds of the people passed a constitutional amendment to repeal the 18th and turn the alcohol legalization decision exclusively over to the states.
Do you think you can get even one-third to legalize maruijuana much less all drugs?