This was accomplished with profligate use of fossil fuel based fertilizer, it’s a trick you can only do once. And nobody produces enough value on their own to become a billionaire, you have to be in a position in an organization where you can skim off the labor of a lot of people.
I'm thinking if population growth continues to shrink and go negative and automation continues to increase, production will stay constant or even increase, even while population decreases. Which would mean that each individual would get more riches with less work.
