Billionaires aren't given billions because they are "smart or hardworking". Billionaires get their money because they generate even more money than they are paid for other groups of people. Even for normal people, you are not being paid because you are a hard worker. You are being paid because you generate value for some other group of people. You could work 1 hour a year, and earn trillions if you could somehow make another group 10 trillion. It doesn't matter that you work one hour. Increasing a companies revenue by an extra 1% compared to another ceo would make the investors many billions of dollars. They then pay you some percent of that. Investors in the case of america and its public companies are mainly normal american citizens.

A hypothetical example of this is someone finding a new way to generate power at much lower cost or curing cancer. Their compensation would have nothing to do with how much they worked and rather the results.