“If it was difficult to grow marijuana yourself they would have legalized it by now and started taxing the crap out of it like they do for cigarettes.”
But you know the quality would be inferior and the price astronomical.
A booming black market in better, cheaper marijuana would spring up so fast it would impale anyone standing in its way.
Very little change would result, I think. Do you really see drug cartels submitting to government regulation, or accepting exclusion from the market?
That is precisely why, if it is made legal that it should remain mostly unregulated and untaxed, with no criminal penalties for private growth or sale. As long as the price remains close to the true market price, no black market will develop. Drug cartels would fail to compete. They only compete now because of the enormous profits offered by a black market.