The US is spending one billion dollars per day in Iran

Imagine with me that we let the middle east eat itself and we put America first for a while.

What domestic problems could be solved with one billion dollars per day?

We needn't have crime, poverty or preventable illness. We needn't have hunger. We could be prosperous and free. The USG, apparently, has the money/credit. They do not actually need to 'pay for' anything.

Or maybe my simple analysis is incorrect. Is there a structural feature to borrowing one billion dollars a day to protect a nation halfway across the world that makes that less of a deficit and debt hit than if we spend the same money on Americans in America?