Quote from trader_arb:
This actually worsens the problem. The skilled will leave for better opportunities, while the lazy, unskilled garbage stays behind and drains resources from the productive.
Exactly. And without skilled immigrants, who will the entrepreneurs hire? Walk into any math, engineering, economics or finance program in any university in America and count the number of American faces. There are almost none. Americans have become lazy. They're all doing majors like "women's studies" (a.k.a. "lessons on the acquisition of government cheese").