You can absolutely buy food with bitcoin from someone who accepts it.  If they don't accept it you'd have to exchange it for whatever they do... Like when you travel to another country.  Surely you must be trolling because there is no way you can't understand this.

If your point is that bitcoin has failed because it isn't ubiquitously accepted everywhere in the world after being barely known of or understood for a handful of years then that's well... dumb