So let's see.
Leads otherwise law-abiding folks into crime. Possession makes them a criminal.
Creates underworld of black-market suppliers. The enhanced profitability of production (production now has greater risk, therefore less competition somebody's gonna pay for it) attracts competition. All criminals -- by definition.
Competitors cannot seek protection from the law. Increased costs, violence, competition, costs, violence. Ad infinitum.
Diversion of vast resources to enforcement.
Corruption of law enforcement -- from resources, and from criminal competitors seeking advantage.
Loss of respect for law and authority.
Widespread flouting of law and authority.
Breeding loss of respect for law and authority.
Repeat as needed.
We don't learn a goddamned thing.
And as an alcoholic and therefore drug addict, I harbour no affection for any drugs.
But Jeezus Fucking Kee-Rist. . . .