The thing is, when most of your money is in illiquid assets (stock, in this case, or houses, etc.) you can reliably get an extremely low interest rate loan against those assets. What does that mean? Let's say you have 10B equity in a company, and you want to buy a used 747 Jumbo Jet--a steal, at $500,000. You only have about $100k liquid cash on you at the moment. No problem! Go to a banker, take an extremely inexpensive loan out against your 10B (think less than 1% interest), and buy your jet. Because it's not income, it's not taxed. But yes, these people do actually have access to that much purchasing power, it's not just abstract numbers.