They will pay zero taxes, only low interest on the loan (below 2% typically). It's called "Buy, Borrow, Die" strategy. When they die, their heirs inherit the assets, but here’s the magic loophole: The heirs get a "step-up in basis" which means the cost basis of the asset is reset to its current market value. This erases all capital gains taxes that would have been owed if the assets were sold during the billionaire’s lifetime. Average person can't get 1-2% loan against their stocks (if they even have any).