One of the reasons behind the dollar strength is that the US has a huge population.

Even if the central bank might does a bad job and make a mess of the economy, the activity of 350 million people is hard to ignore.

Is it enough to _fully_ sustain the US dollar?

Who knows, but at least there is a floor, even if everybody stopped using US dollars for international trade.

U.S. has only 4% of the global population.

I think this is a big part of both the impact of globalization and the U.S's waning power. Back around 1950, right after WW2, the "first world" (the developed west, not including Russia or Warsaw Pact countries) had a total population of just over 500M, and the U.S. was 150M of those, just under 1/3. And the remainder were largely dependent upon U.S. capital, machinery, and technology, having just bombed each other back to pre-industrial times.

Today, the developed world is about 3-4B people, and the U.S. is 350M of them, less than 10%. China alone has lifted about 500M people out of poverty and into the middle class in the last 2 decades, a population larger than the total population of the middle class in the U.S. The population of Asia is around 4.86B, 15x the size of the United States, and an increasingly large number of them are living a lifestyle close to what Americans enjoy.

I mean sure but... How much do you want to hold the Yuan? China has always had a huge population but nobody considered the Yuan the same way.

Nobody thinks of the Indian rupee this way today.