How much illegal liquor is brought in the country now?
It's all about profit margin. When drugs are legalized the drug lords will no longer have the high profits they now enjoy as an incentive to continue their activities.
The people who are most interested in keeping the War On Drugs alive are those who profit from it. Legalizing Marijuana or any of the stuff Congress likes to call controlled substances, would eliminate the multibillion-dollar profits and quickly reduce the market size. Users would be buying in stores licensed and taxed by the government, with the tax revenue going into rehabilitation programs.
Even worse for the drug barons, the glamour of doing something illegal would be gone for the teenagers, and there would be no reason left for the drug gangs to hire them to push the stuff in school yards and keep the list of customers multiplying. No more knife fights and gun battles for market territory. No more no-knock raids on innocent people. No more dealers standing on neighborhood street corners. No more confiscated property.
Legalizing and licensing knocks out the profits.
Politicians who support the War On Drugs are doing so for one reason only, they have a lobbyist funded by a drug baron slipping large quantities of cash into their pockets to keep the drug profits flowing. Their interest is in keeping the War On Drugs alive, well funded, and managed with the same bungling incompetence that has filled the prison system with bottom-level dealers and users, and left the big operators untroubled and the price of cocaine and heroin profitably high.
Wouldn't drugs still be illegal for teens?
But if you're saying that because drugs would be legal for adults, the glamour would be gone for teens, you're dead wrong.
Despite the fact that every survey shows that teens say marijuana is easier for them to obtain than alcohol, twice as many teens use alcohol over marijuana (34.6% vs. 15.8%). You can find it here.
Care to explain how this fact fits your theory?