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.
Because we’re not criminally insane.
But since we’re on this fascinating topic, here’s a Youtube video about other things people have tried to substitute for coffee during the American civil war. (Hint: not beans.)