Okay how about this.

No more billionaires. None. Once you reach $999,999,999.99 if you make one penny more, we take away all your money and give it to the poor and needy and in return you get a special ID that allows you to take anything you want from any store in the country for free. A billionaire can effectively buy anything they want at any time anywhere anyway, so that changes nothing about their lifestyle. But you can no longer use your money to bribe politicians or influence the global economy. You just get to win capitalism for the rest of your life. And every penny of your money goes toward actually improving the lives of everyone else around you.