This is true. We definitely benefited from the Nazis in that we got their best scientists and thinkers except for a few, and those remaining didn’t always have “critical mass”. I like to point out that without “immigration”, what would out atomic and space programs have been like. It’s not the numbers of immigrants, it’s the “who”.
When the USSR broke up, the US kept their quotas on. A lot of Jewish scientists, doctors, and engineers wanted to come here but couldn’t. So they went to Israel, and they have an open door for Jews. They try to help to get them established with a place to live and a job. So there were ex-Soviet nuclear physicists running street sweepers there.
Ok the handfull of brilliant scientist doesn’t mean we H-1B visas by the hundreds of thousands.