I don't think we'll see born-in-the-USA Americans moving to Shenzhen anytime soon.
But a huge fraction of our workforce is immigrants who have given up their homeland and distanced themselves from their families and communities in search of opportunities here. The fact that we're driving them away now does not bode well for our future economy.
If the immigrants that we've allowed to come here are so fickle that they would leave for China if China presents better opportunities, I would prefer that they leave now and get it over with. My country is not an economic zone for extracting value. It's my home.
I'm not talking about land speculation. I'm talking about creating businesses and jobs for everyone. I'm talking about hard labor that's necessary for our society to run. We're not better off picking crops while China's tech economy becomes #1.
If someone said "Americans do X", there would be some pushback about "not all Americans". But somehow it's normal (expected even) to bunch all immigrants together into the "they were all desperate and decided to jump the fence" pile.
It's actually surprising that this point is so hard to understand.
Those who stood in line as you say also want to take people out of today's queue. Legality doesn't have much to do with it. In Britain it's called pulling up the drawbridge.
But a huge fraction of our workforce is immigrants who have given up their homeland and distanced themselves from their families and communities in search of opportunities here. The fact that we're driving them away now does not bode well for our future economy.