The Massachusetts marijuana industry is on the verge of an impressive milestone: $4 billion in revenue since recreational sales began in November 2018, a total that has also netted state and local governments hundreds of millions of dollars in taxes.

But when the state surpasses that mark — likely in the next month or so — there may not be much celebration from its roughly 250 cannabis stores.

That’s because a newly legal industry previously seen by giddy investors and entrepreneurs as the next gold rush has turned out to be more like an ordinary commodity market, with a massive increase in wholesale supply and retail competition over the past year causing an equally massive price crash. As a result, many operators are watching their slice of profits shrink even as the overall pot pie continues to grow.

“Everyone was expecting it would be a high-margin boom, but now it’s a race to the bottom,” said Kobie Evans, co-owner of the Pure Oasis marijuana store in Boston. “The market shifted very quickly within the last 12 months, and for investors, there’s a low probability they’ll get the returns they once anticipated.”