It's very difficult for foreign nationals to come here for education or H1Bs.
So most of them have to work hard to prove themselves. They then get the same opportunities (and pay) as an American. They come here, they build a career, they build a life, and they build companies.
We're literally taking the best and brightest from other countries. These are their most valuable resources, and we have the means to attract them, bring them here, and make them Americans.
If we're truly America First, we should want to do this more, rather than let the smartest world citizens stay in their home countries and start competitors to our companies.