How high does the drug trade go?

Yes it is. When a government that uses its Constitution for toilet paper instead of enforcing it moves a popular product into the black market, it immediately becomes a high-risk business. Not the risk of losing money that is usually associated with business, but the risk of being arrested and imprisoned. Only the highest risk takers will engage in this business, and to be willing to take the risk they must be guaranteed a high profit, so the price rises by several orders of magnitude. (Marijuana is a weed but it retails for about $10,000 a pound, three and a half orders of magnitude higher than the price of other popular vegetables.) Except for a few naive fools who will be quickly eliminated, only criminals will be interested in this business.

Career criminals have their own business methods, and one of their priorities is to minimize the risk of doing business. To that end they use some of their enormous profits to bribe law enforcement agents and other key government employees who have the power to protect them from arrest and prosecution. America learned this 90 years ago during the dark days of alcohol prohibition, which created the Mafia, but we are a people with a short memory. So many cops and D.A.s were on the take that the location of "speakeasies" was well-known and they were rarely busted.

They also use their money to establish headquarters in countries where the government is corrupt, ineffective or easily intimidated. Mexico is nowhere near the bottom of the list of the world's most poorly-run countries, yet even Mexico's police and judiciary have been compromised by drug money. So imagine what it must be like in a hopeless place like Somalia, Tajikistan or Burma.

The point is that commerce can never be totally stifled. If people want a product, they will find a way to acquire it because there will always be someone willing to take the risk of providing it, even if it means corrupting their infrastructure. You can get drugs in American schools, with their nearly complete suppression of privacy and civil rights. You can get drugs in prison. Drugs were even available in the old Soviet Union.

You cannot eradicate an industry for which there is a sizeable market. The law of supply and demand tells us that. People want drugs so there will always be a drug business. You can have it taxed and regulated like alcohol, so it's run by more-or-less respectable corporations and it provides a sizeable chunk of your government's operating expenses (that's the real reason Prohibition was repealed in the depths of the Great Depression). Or you can have it sold on the black market, enriching criminals who engage in gun battles on your boulevards, and the drugs become so expensive that users turn to robbery to pay for them.

Oh yeah, in the case of opium, which grows in fucking Afghanistan of all places, the roughly ten billion dollars in annual profit go to the Taliban and Al Qaeda because apparently that's the way Americans want it.

Go figure.