The US attracted the best and the brightest. If you insist on sending them back because they are "immigrants" then the loss is not just theirs.From the article "Many innovators in Silicon Valley come from overseas; 42 percent of engineers with master’s degrees and 60 percent of those with engineering Ph.D.’s in the United States are foreign-born."
Do you know why Chinese and Indians population in Universities are increasing? Because in those cultures being a geek is cool, unlike in US. In China and US, the topper in the school is the super star unlike in US where it will be the college football captain. The toppers from such places come to US because the US universities are far ahead in higher education. But if you send these people back, this lead in education will slowly evaporate as the best students go back to their country instead of staying on and becoming entrepreneurs and professors.