The theoretical cap for this, if you include every human being on planet Earth, is 7 billion/month. This translates into $84 billion annual revenue. Google's r

The theoretical cap for this, if you include every human being on planet Earth, is 7 billion/month. This translates into $84 billion annual revenue. Google's revenue last year was 146 billion, and it operates not anywhere near the theoretical maximum. Most of that revenue is advertisement.