Sure, there is a limit to how much people can pay for a drug, but with the most addictive drugs, addicts don’t limit themselves to their own budget. If they don’t have money to pay for the drug, they will go out and do anything to get the money. So, I think your idea that you can eliminate 90% of use this way is very optimistic. Maybe you can reduce it 20 or 30%, but I doubt much more than that.
“If they don’t have money to pay for the drug, they will go out and do anything to get the money.”
Even if addicts quote “do anything” to get the money they are limited in their ability to get money. You are very unrealistic in your belief that drug addicts have some enormous ability to make money.