Except that the government can regulate the legal marijuana operation to death like they did tobacco.
But if you just grow a little patch of Weed next to the cucumbers, you can pull some serious change on the black market and the government will think it is grown for personal use. If government weed is $400 an oz and black market is $200 an oz, you can make $100 an oz.
Not only that, the legal sellers have to lawyer up just like the tobacco companies.
People can legally grow their own in CO, up to 6 plants. Despite that, a billion dollars worth was sold in the legal market.
Except the regulated "government" stuff runs about the same per ounce as the black market stuff, and is far better in quality. It is only slightly more expensive with taxes added, but thus far, that isn't stopping people from buying at the regulated shops. There is still a black market, but the cause of that is generally cities in CO that have opted not to allow the legal shops. In those cases, the city governments are outright supporting the Mexican drug cartels and the black market.