Andy Grove of Intel fame was a Jewish refugee who fled post WWII Europe to the US (Gordon Moore was born in San Fran and Robert Noyce born in Iowa however, where the actual founders of Intel).
Pierre Omidyar of eBay of course is a Frenchman who moved to this country with his family when he was 6 years old.
Yahoo! founded by David Filo ( cheese head from Wisconsin) and Jerry Yang who came to this country with his family when he 10 from Taiwan.
None of these people came to the US on work visas.
What about student visas? What about the students that came to study in the US, obtained bachelors and masters degrees, and then were denied to work in the US?
"If there isn't a population problem, why is the government putting cancer in the cigarettes?" -- the elder Steptoe, c. 1970