Two things:

A) With great power comes great responsibility + making the world better through eradication of diseases, heightened food and economic security, improvements to the stability of nations, access to shared research and information, and increased personal agency makes it all better for Americans too.

B) Given you probably find (A) uncompelling, you should familiarize yourself with the concept of "soft power" and try to learn a bit about how relatively inexpensive it's been for the US to have an outsized influence around the world over the past many decades (outside of stupid, unnecessary wars, of course) and the benefits that's yielded for our economic and geopolitical interests across the board. If you'd prefer to not though, don't worry -- provided you're around for a couple more decades, you're going to get a crash course in the alternative.