Why doesn’t this exist?
Take dried beans, roast 'em, grind 'em, and brew some bean juice?
I have no idea if it would taste good or not, but we don’t know if we don’t try.
Edit: I need to see what dried beans I have and maybe go shopping. I will give this a try with a couple different types of beans and report back if I fart or not.
A lot of things in botany have similar names, but are totally different things. A “strawberry” is a berry only by names (it’s closest relative is the hazelnut, IIRC), a “peanut” is no nut, either.
So it should not surprize when one learns that the Cofea plant is a Rubiaceae family plant, not a Fabaceae/Leguminosae family plant, i.e. what we commonly call “beans” like green beans, peas, or, amazingly, peanuts. It is just called a “coffee bean” because it reminded someone back in time of a bean, shapewise.
So if it’s not a bean, what is it? It’s not the fruit, so is it the seed?