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.
Ignoring the fact that coffee beans aren’t beans, for the same reason we don’t make tea with just any leaf. Someone braver than you tried it and it was disgusting.