Whatever amount of money is sent to another country is money not spent here.
All illegals need to be booted out, if we need legal immigrants that is a different story. I am not convinced we need as many as we are told we need.
It doesn’t get sent there and disappear. You can’t eat U.S. dollars, so they have to be exchanged for another currency (in which case they come back here anyway) or used to purchase something that is bought and sold using U.S. dollars. The dollars eventually come back here, one way or another.