This ^

Cool, let’s pull out of all of our military bases globally and really speed up Chinese unipolar hegemony. Sounds fun! We can’t remove ourselves from the position we inherited in 1946 without disrupting the global power balance on a massive scale.

Idealism and global geopolitics don’t mix. There’s no supranational organization to mediate disputes between countries, at least yet. Without that, brute force/power projection is how it works.

Is it not? It’s possible that the amount of funding required scales exponentially with relative military power, as you have more nations that would be willing to dethrone you, so you must be able to withstand your opponents’ cumulative military strength.

Even with as much as we spend, China is a formidable military threat.

Debatable. R&D funding, job creation (including at overseas bases and embassies), massive economic benefits from being the world reserve currency, etc.