Wouldn't it be terrible for other countries?
No, because many of these intelligent people wouldn't have the resources to succeed in any other country. Elon Musk would've never succeeded with Tesla or Space X anywhere else, because the US has the smartest people from all over the world.
Their accomplishments in the US benefit the entire world. The internet, for example, was invented in America, but almost the entire world now has internet.
Why do we deserve to live a better life than people on other countries?
- Our ancestors built this country, and it is our responsibility to maintain its greatness.
- These people you want to bring in will destroy us. They are responsible for their own country's shit.