One could claim that this is the current state of the American aristocracy. For all of the wealth inequality, I see very few instances of "Zuckerberg Theater", "Gates Hospital", or even a "Brin college".

What, $40b for a dying social media company that no one will remember in 25 years vs literally anything useful and enduring? My post office is 130 years old!

Those were needed because buying politicians and public favor was hard.

Now you just buy media.

Perhaps I am misunderstanding your comment, but one of the largest hospitals in the Bay Area is quite literally called Zuckerberg Hospital: https://www.zuckerbergsanfranciscogeneral.org/

Gates has given many billions to public health initiatives as well

Yes. ~7.5% of the cost contribution bought them the name on the building.

I think that the Gates foundation has spent hundreds of millions of dollars on malaria initiatives alone. When I lived in SF, Zuckerberg Hospital was pretty close and it was pretty gigantic. Mark Benioff has spent hundreds of millions on Childrens hospitals in Oakland and SF as well.

Maybe we're converting to more of a Roman- or Mongol- or Aztec-style empire.

Not quite so simple. The United States has many different internal interests that disagree on many things between them, but align in spreading American influence globally through programs like this and many, many others.

However, it also has other factions, especially since Trump and his often bizarre, even irrational takes on what's important, basically took over the Republican Party, making a number of Republicans now also shun programs that previously, they wouldn't have so much as blinked at. This is cowardly of these people, but it's also par for the course with ideological shifts in political leadership.