So first you export industries to China. Then you import engineers from India to help British engineers lose their jobs. This is why Brexit happened. For the same reason Trump happened. Too many elite and comfortable people didn't care about the rest of their country's citizens who were getting a bad deal. While the rich and connected classes seemed to be doing OK, no one cared about the rest. Enter Trump. Bye EU.
The difficulty with tying to explain anything to you, Alan, is that you don't appear willing (able?) to take any new information into your mind, digest it and understand what has been explained.
Your single response turns not into consideration of the new thought, but into defence, rejection and instant reversion to cant; in other words, your mind is a closed loop, with you imprisoned within. Set yourself free; have a look beyond the borders of your self-created cage.
I explained, clearly and with examples, the vicious circle of increasing decline that overpayment for low services produces; the same holds true in the other direction, where overpayment of high skills,
where they are not severely limited in supply (there are thousands of engineers) leads to exactly the same thing: somebody else can always do it just as well, possibly better, and if you hold out for top dollar, you'll often get nothing. Trump should know that better than most, don't you think?
The only way you can 'protect' your single country is by building walls and laying minefields, not just with Mexico, but around the entire US perimeter and, as with some other totalitarian (where you're headed) states, not so much to keep invaders out, as your own people captive within.
Do that, and your much-vaunted national sense of flag-waving, comparatively recent heritage (and European identity derived from your ancestors) will vanish as you turn into a sort of post-apocalyptic land of hillbillies, gunmen and junkies. And you won't even have Hollywood left to keep the money rolling in from the rest of the world. Alternatively, you could forge a new relationship with the Castro familia and feel quite at home.
Either way, you'd bring down not just your own spot under the Sun, but the rest of us with you. Which is why we care.