The only thing you have ignored is the fact that individual drugs are not part of discrete markets. If a dealer loses a revenue stream in cannabis why does that

The only thing you have ignored is the fact that individual drugs are not part of discrete markets. If a dealer loses a revenue stream in cannabis why does that mean he will not continue (and start) in other areas. While we are on economics there is another issue you've ignored. The fact that legalization removes a revenue stream for the drugs gangs. They will want to expand markets - that means new drugs and new problems. If they cannot supply cannabis why is it illogical to imagine they would not expand the heroin/coke markets. If you want some "insider info"; we did a couple of investigations into drugs gangs last year. There is already a lot of market control within the gang infrastructure - they use fairly sophisticated market strategy to expand usage of underperforming drugs in an area for example.