How is the US benefitting from this?

Draining the resources of geopolitical rival without dead troops, weapons exports and lucrative contracts for reconstruction.

You should read war is a racket https://ratical.org/ratville/CAH/warisaracket.html

The guy who wrote it, smedley butler, was a highly decorated major general

Capital loves war which is why the US has been at war for something like 92% of its miserable existence. Of course the average person gets fucked