There's a ton of money in it. The arbitrage is that one farmer can produce hundreds of pounds of product but cannot possibly warehouse and sell it all themselves. The resulting wholesale prices make setting up a shop that charges retail prices an incredibly reliable way to make money.

There is no mechanism, as there is in food, to support farmers or to control consumer prices. There is also no government funded free marijuana program. It seems like it would have analogs, but marijuana is truly a unique market.