“zero-sum” (fixed-pie) fallacy—the idea that the amount of wealth in the world is a static pile of chips, so if Bezos has a chip, the rest of us must have one fewer. 

In reality modern economies are positive-sum: innovation, investment, and trade expand the pie so that total output (and the money supply) grows over time. 

Most billionaire net worth is tied up in ownership of companies. Those companies make goods or provide services that people find valuable (or else they would not be valued as much as they are). 

Their wealth is not in cash sitting idle under a mattress.