They don’t sell, they take loans instead:

At some point, one might expect that the ultrawealthy would have to sell their shares to finance their lifestyle. Do they? In selling those shares, wouldn’t they have to pay a capital gains tax?

For most of us, when we own property or stock that has increased in value, it doesn’t mean anything to us unless we sell it. But those with great wealth can access that wealth without paying taxes by simply borrowing against their assets. And that is what our richest Americans do. 

Billionaires like Larry Ellison and Elon Musk borrow huge sums of money to support their lifestyle, pledging their stock as collateral. This borrowing is entirely tax-free and comes at good rates. In addition, in recent years the growth in stock value more than compensatesfor any interest that might accrue. To pay the interest and pay back the loans, they simply borrow again.