We could cut the size of the military... but simply making the observation that we have a large number of people doesn't explain anything. China's military is 2

We could cut the size of the military... but simply making the observation that we have a large number of people doesn't explain anything. China's military is 2x the size of the US by number of people. It certainly doesn't follow that the richer and more valuable a country becomes (and therefore more expensive personnel), the smaller their military should be.