If you're able to interact with the smartest people in the world - and not just your own country - you end up forming more effective and larger companies. Which in turn create jobs.
If you shut out your country to the rest of the world, the next Google will be founded somewhere else.
And I'll dispute your claim that the US has enough talent. There was a submission on HN recently about the top deep learning papers. Go through it. Count the number of American-born people. Geoff Hinton? Yann LeCun? Russ Salakhutdinov? Demis Hassibis (of Deep Mind)? Virtually everyone on there was born somewhere else. They're not Americans, but they're mostly working for American companies and contributing their talent to YOUR economy.
[0] https://github.com/terryum/awesome-deep-learning-papers/blob...