We already waste too much money in the United States trying to be the world police, and there's no good reason for it any more. We have too many of our own problems to deal with to waste so much money on that crap.
The notion that the US military has been a force of good for the world needs to be abandoned. It serves only to encourage the US to attack more countries, as killing millions more Asians would be viewed as the more moral option than allowing Chinese influence to spread.
America, every European colonial power, Britian, the Soviet Union, and Imperial Japan have each had their share of atrocities where they were unchallenged superpowers.
There's a lot to be said for multipolarity.
Additionally, I'd point out the US funds ~1/4 of the UN (China next at ~1/10). Which seems pretty generous to maintaining internal order in a broad way.