The US owns the money printer to the world trade currency (USD), and has the military force to defend this unique position, so of course it can afford to outspend everyone else.
No, kids, if Saudi Arabia suddenly started selling all its oil in Euros or Yen on renminbi, the US would not send the Sixth Fleet off its shore, any more than it did so to force KSA to use the US dollar to price its wares in the first place. Saudis (and Russians, and Chinese, and everyone else) use the US dollar because they find that a) using it is more convenient than another hard currency like the Swiss franc or British pound, and b) no one else wants riyals, rubles, or renminbi.
I can make the same argument without mentioning the military - we benefit from a virtuous cycle of having the most dynamic economy which allows us access to credit to improve it, making it even more dynamic, and we simply pay it back as a lesser share of % GDP later.
It has nothing to do with the federal reserve and everything to do with risk tolerence.