I can't speak to this from personal experience, but I constantly hear the accusation that any sort of solid study on say herbals is going to cost millions of dollars, and that no big-pharma company would even bother to sponsor such a study because they can't patent the result (because it's an herb).

They could patent a delivery mechanism, or isolate some compounds from the herb that work almost as well (that's not exactly an unusual result either). These arguments fall down because they don't make any sense.

There’s at least one pot based drug on the market. So I think there must be some way to profit from medicines that were known anecdotally to be medicinal in herb form.