And no one has to worry that some other billionaire is going to send an army to conquer his or her estate and holdings by force of arms, slaughtering all the employees and destroying the inventory.
They don't have to pack the basements with food for the winter. Their fleets of cars and other ridiculous collections can be safely stored away from the environment and peasants (meaning anyone poor, like millionaires).
Governments make rules to favor them and do the job of selling it to the masses. They don't have to do their own PR. In fact, the media will do the PR for them and it won't cost them anything, for the most part.
They can bury their pecadillos on private islands, secure in the knowledge that, even if word gets out, word won't get out, for reasons. And besides, no one will really care, because governments and media will magically turn it from horrible scandal to mild eccentricity.
And if they don't like the government, well, now, they can just buy one.
No idea what happens if they try to return it, though.
Sure you can acquire a private fleet of jets and cars now. But given that you rarely if-ever drive them it's no different than a fleet of rare animals.
Sure you can play video games and watch sports on TV but is that really much better than watching sports from a private suite?
I will conceded that their life expectancy has basically doubled but I don't think there's anything you can do as a king to fix that. If you don't hoard all the wealth it's not like life expectancy immediately doubles. A rising tide raises all ships but the tide takes centuries to do that lifting.