Earlier quoted context omitted.
Because we benefit disproportionately from world peace, uninterrupted shipping, and the world economy using the U.S. dollar as its reserve currency.
The dollar became the world currency by accident after the OPEC started pricing petroleum in dollars. We're starting to see a slow departure from that. If we did not spend those extra tens of billions per year in projecting power, we could better serve our students, workers, retirees, infrastructure, etc. Instead, they go to ensuring Japan, Korea, Philippines, etc. don't have to spend so much on defense. As China asc…
History's not on your side for that one. You're talking about the country that, plagued by pirates disturbing its coastal shipping, went to massive expense to construct an enormous system of inland canals running parallel to the coast that the pirates couldn't reach.
If Chinese merchants wanted the sea kept clear, say because they wanted to trade with nearby islands, they had do that in their own private capacity. https://en.wikipedia.org/wiki/Koxinga