Pharmaceutical research tends to focus on patentable molecules, not unpatentable plants.

That's why I didn't mention the pharma companies. If it legitimately helps people there's still tons of money to be made off of it, such as marketing it properly and some optimized form for consumption - like how Epipen scammed the public with their 'form factor' patents which held up generic brands for years.

You can patent the use of a product derived from a plant.

Nobody currently, though fzeroracer seems to think it is unreasonable for scientists to do this.