Who the f*ck is going to buy government taxed and regulated (god only knows what they'll do when "regulating" it) pot when you can just buy it on the street cheaper?
And yes, I've heard the Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!) talking point about how it will flood demand and drive prices down pushing dealers out of the market (only Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!) libs who don't understand basic economics believe this). It won't, that's Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!), drug smugglers/dealers (billion dollar industry) aren't going to stop selling pot just because it's legalized, they will continue to sell it at a price below govt. and if they don't have any regard for the government now, they sure ashell aren't going to all of the sudden care because it's legal.
Other than that, it's a superb idea (besides the whole health, safety and welfare of the state thing, ya know having a bunch of stoned people driving around running over little kids like degenerate alcoholics).