Disclaimer: I'm far from an expert on economics. I apologize if the question seems poorly asked or not clear.
Take for example the drug trafficking business and cartels in the past. It seems to me that the production cost of illegal drug substances was quite low. Most of the usual substances back then were either a form of plant or extracted from certain kinds of plants.
In contrast, the demand of those substances was tremendous, mostly because of their unusual properties and effects on the human body.
How this low production cost - enormously high demand combo affected the economy of the countries where drug trafficking was taking place?