It's very hard to know what's the most profitable LOB of crime organizations here. What is well known is that they operate on a wide "portfolio" of products and services since there are strong dependencies between them. Drugs, weapons, bank robbery, ATM stealing, truck robbery, kidnapping... the list is long.
Drugs is a relevant LOB because it employs a great deal of terror on the human structure of the organization. Debt with a drug dealer is usually seen as a death sentence. So the dealer knows he can manipulate those who cannot pay their debts by forcing them to commit various crimes as compensation. Dealers don't need money to finance crimes, they do it mostly through terror. Drugs are just the foundations.
Black market. If the legal drug is sold for $15, drug dealers would sell the same amount for $10. Like the do with stolen medical drugs sold mostly in slums.
Government/private companies would have a hard time trying to sell legal drugs anywhere near slums. Not only the dealers would exterminate the workers of those places, but would also steal the products to resell them.
I'm pro drug decriminalization. I believe people should be free to experiment anything they want in their lives, of course, being properly accountable for that. But my problem is with people that generalize the success of ANY decriminalization campaign only because Portugal made it right. There are so many variables in this game, so many social and cultural pre-requisites that we cannot treat this subject with just a couple of lines.
I appreciate you time articulating your ideas while commenting my point. I think that's the type of exercise that this subject deserves.