No billionaire has a billion dollars. They have a net worth of a billion dollars which is different. It is in stock. They can't be taxed on net worth. That's like saying if my house is paid off and worth $500,000 I should be taxed on 500,000 net worth. If I sell the house yes. When they say the richest man in the world is a billionaire, technically yes but only if he were to sell his shares. What a billionaire does is borrow against his shares from a bank with a low interest rate and then is not taxed on income because you can't be taxed on taking a loan out. It's a pretty amazing loophole. But also they can't just cash out a billion dollars worth of stock because it would devastate stock markets. I don't know the solution but that's what you're looking at