The uber rich spending is generally via “business expenses”.

For example: Elon doesn’t own his private jets, SpaceX does. When he takes it down to Hawaii for a 15 minute investor meeting followed by hanging out with them for the weekend at the nicest hotels with all the fixings and flys back, that’s all business expenses that he “derived no personal benefit from”, so SpaceX writes it all off as a business expense, thus reducing their tax burden and he never personally gets taxed for it.

A less egregious example that happens considerably more: a person has a rental property that resides between their normal living area, which they consider the “home office”, and an area of interest they travel too. They go to the area of interest, but make sure to stop by the rental on the way there and back. The milage from the home to the rental is business miles, and thus they can deduct the travel expense from any business incomes.

I am not advocating for any of those, but it doesn’t really matter if these business expenses are legal because the IRS doesn’t have a great way to determine these minor abuses, and certainly doesn’t have the people power to track it down.