Basically, once you're this rich, you can take hundreds of millions or billions of dollars worth of loans to cover anything you'd like to spend. Now, you can make sure that you're actually "losing" money in any given year by having (almost) no realized income. Then, at the end, you die, having never paid taxes.
https://www.nytimes.com/2021/06/09/briefing/tax-jeff-bezos-w...
https://www.propublica.org/article/the-secret-irs-files-shor...
EDIT: Yes, this is a big part of why there's now a common argument that unrealized (but very large) capital gains should be taxed.