A lot of people think that pot is going to be some revenue god send so they tax the heck out it which creates a huge black market. People need to think of it as a 'little revenue generator' and a 'little cost saver'. You are probably going save more $$$ on the law enforcement, incarceration side of things and generate less $$$ on tax revenue.
The problem is the first one is easily measurable. The second one, not so much, so it is fake news.