I live in a legalized Marijauna country and there is no black market. The prices in the legal stores are actually lower than the former black market prices.
There were Conservative politicians who got up and publicly said that toddlers would die cause they'd eat marijuana plants grown by their parents!
I wouldn't blame the business plans so much. A lot of them applied for licenses but didn't get theirs approved till after the huge players did. By then, the market had already consolidated.