Growing is totally separate from selling though. I don't know about the UK case but in Canada, there was intense opposition from Conservatives towards any amount of pot being allowed to be homegrown.

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.