A huge point of legalizing is to take away a large percentage of gangs’ income by making legitimate businesses replace their supply chain over time.

Obviously criminals are still going to be deep in that as well, especially since they already have a lot of the supply already in place, but people are more inclined to work with police if they aren’t at risk for being hassled by them for their drug use and/or business with said drugs.

It’s basically death by a thousand cuts (over time) for criminal enterprises.

Also, if there’s no reason to be scared of the cops or the justice system (that’s rich!), you’re also more likely to cooperate with police if your legitimate drug business is being squeezed or compromised by criminals.

This should’ve already happened, of course, because now the problem really is the amount of money criminals have made off of the illegal drug trade, rivaling many nations. That money is being laundered and injected into legitimate businesses and investments, solidifying criminals’ leverage over the economy.