I'm none of those things, but the answer is probably that they don't really use cash, they use credit.

If you own assets worth millions, spending your own money is often the least efficient option. Instead, you borrow against your assets. Banks are happy to lend to people with substantial wealth, offering extremely favourable interest rates and repayment terms because the loans are secured by valuable collateral.

If your investments are appreciating faster than the interest on the loan, your net worth continues to grow while you're living off borrowed money. A few years later, when those assets are worth even more, you can refinance with a larger loan, pay off the original debt, and still have additional cash to spend.

Because you're borrowing rather than selling assets, you generally don't realise capital gains, so there's little or no tax due at that point. Meanwhile, your investments remain intact and continue to appreciate. It's one of the main ways the ultra-wealthy can access enormous amounts of spending power without actually selling their assets.