What do you mean we send them away? Should we hold them against their will? If they want to stay there are ways to stay.
Also- the US doesn't owe everybody a citizenship.
https://www.uscis.gov/citizenship-resource-center/naturaliza...
I had a friend with a CS degree ask if I would marry her because she didn't want to go back to China and couldn't get an H1B.
167k for Australia (US has almost 13x the population of Australia)