But users could care less what the dealers do with the money.
What's your point? I agree with you somewhat, although I think that if given the choice users would probably rather buy from sources where they knew the money wouldn't go to support bad people who do bad things, but they don't have that choice. I don't really see your point. Are you saying that users would buy from the black market anyway if we legalized it? I don't think that would be much of a problem. Black market marijuana is not cheap. You don't know what is on it, whether the growers were using toxic pesticides or something like that on it. You don't know what kind of thugs the money will support. And Mexican marijuana is seedy and harsh and people wouldn't buy it if it wasn't so much cheaper than the much higher quality domestic product.
The only reason marijuana costs hundreds of dollars a pound in the case of Mexican and up to thousands of dollars a pound in the case of domestic indoor grown marijuana is that it is illegal. It's not an extremely difficult plant to grow and it is possible to get well over a thousand pounds of usable product per acre. When American farmers start growing it on large farms using modern agricultural methods and mechanizing the process as much as possible they will cut production costs to a fraction of what they are today. More importantly, there will be no more risk of seizure, no more risk of arrest. They'll be able to drive a load of it down the highway in something like a Budweiser truck rather than breaking it down into couple of hundred pound trunk loads and paying mules thousands of dollars per load to transport it. There will be far fewer middlemen, far fewer who want a huge cut of the profits to justify their risks. Wholesale prices will be low and the only way we'll be able to keep consumer prices anywhere close to where they are today is with taxation.
Black market product would have to be much cheaper for anyone to want to buy it, and if it has to be much cheaper than it is today it won't be worth the trouble and the risk involved for people to supply it. Why buy crappy black market pot from shady people that's likely to be moldy and or have toxic chemicals on it when you can go to a nice clean shop and legally pick from a wide range of quality product for reasonable prices? Like the “coffeeshops” in the Netherlands these places would have product in all sorts of prices ranges, with different smell, tastes and potency levels, but it will be coming from a regulated industry and not from the black market. People will go to the “pot shops” just like we go to liquor stores today. We don't have a big problem with black market liquor or beer and we won't have a problem with black market marijuana if we give people the option of going through legal channels to buy it.