Any adult in CO can grow their own, yet pot stores are doing a booming business.
“So how did medical mj become a billion dollar industry in CA alone, despite the fact that patients can grow their own?”
Because it is heavily regulated. It isn’t totally legal like tomatoes are.
Even in CO it is heavily regulated, you can’t just till up the backyard and start growing it.
Use common sense, anyone could grow a dozen tomato plants. At best you will have fresh tomatoes for a month or so, then you are done for the year. That is why their is a commercial market, so you can get them all year.
A dozen pot plants would keep you stoned out of your gourd all year. It isn’t used as a fresh product, so storage isn’t a problem.
It’s also legal to brew your own beer and wine, and doing so can save you a considerable amount of money (provided you make a decent batch, that is) — yet, most people buy the stuff from stores, ready-made. Brewing and growing are different, but do make a useful comparison. It’s easy to think of reasons to buy,rather than grow. For instance, people might not have the space, nor the horticultural inclinations to grow their own.
However, by the laws of supply and demand; as prices go up more people will grow their own, and vice versa.