I don't disagree. It is the world's premier tech hub. But a fleeting 4 year long ban on immigrants wouldn't turn the city to rubble and leave everybody without jobs as Google and Y Combinator pack up bags and move to Tijuana and Beijing. There are larger forces at play here than that.
Isn't it a bitter irony that someone who became successful in Silicon Valley (Peter Thiel) was a driving force to get a president, whose policies could potentially lead to a bit of a decline for Silicon Valley, elected?
Of course. But it'll do some damage, which will only get worse as time goes on. What about 8 years? 12? If you restrict skilled legal immigration long-term, you're necessarily going to (slowly) drive companies away.
It's not a zero-sum game of open jobs to potential employees.
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.
Sure and I love that those people (highly skilled immigrants) are working for American companies.
But so what? That doesn't demonstrate that the US doesn't have enough talent. It just shows that some people from out of the country were working on something. Maybe if the situation was different then that paper could be exclusively written be Americans. The majority of the worlds most intelligent people reside elsewhere, but the US has nearly 400 million people. It's fine with or without immigrants. Japan is fine isn't it?
Let me end off by saying there's a difference between being "fine" and "exceptional". If you're content with the former, then that's okay, no problem there -- cutting off immigration will be okay. America will survive, there won't be an apocalypse. Like Japan right now -- it's got mediocre companies with a mediocre economy.
Many papers are written exclusively by Americans, but they're often not the best. That's what you're going to have to be content with, if you shut off immigration. Being okay, but not the best.
Imagine that those researchers couldn't go to the US. Imagine instead of Google DeepMind beating Lee Sedol it was a Canadian or Chinese company. Imagine if the first company to roll out mass self-driving cars would be Didi instead of Tesla. It's an inevitability, once all the top minds in the world go to companies outside the US. And as I said, it's not horrible for America, the country will surivive and do okay, but there'll be jobs lost and innovation will go somewhere else.
