Enforcement is lacking, incentives for criminals are extremely high - cocaine, for example, explodes in value from $2000/kg in the jungle where it's made to $20000/kg after it's been smuggled to the US - and quite a few popular drugs can be made at home using basic tools and skills (cannabis, amphetamine, alcohol, tobacco).
Enforcement isn't lacking, it's just done counter-productively. About 20% of US prison population is already for drug offences, and of course it doesn't help anything. There is absolutely no reason to believe that other regulations are or will be enforced in a smarter way.
Enforcement is lacking, incentives for criminals are extremely high - cocaine, for example, explodes in value from $2000/kg in the jungle where it's made to $20000/kg after it's been smuggled to the US - and quite a few popular drugs can be made at home using basic tools and skills (cannabis, amphetamine, alcohol, tobacco).