It's a matter of amounts, not of yes/no. Of course they pay rent and buy food, but in what comparative amounts? If you send half of your money outside the country, where very little of it makes its way back to supporting the US economy, that's worse than if your salary was given to someone who was going to use it all inside the US. If you disagree with that, please provide some numbers for us to use as examples.

Also, please point me to these Americans who save their money. The average domestic savings rate is 5.7% and almost all of that is money stored in US bank accounts and stocks, which in turn is used to help the US economy.