Imagine you're a US doctor. You're one of the best doctors in the world, and you've quite well paid.
Now suppose, in exchange for some of the long hours you put in at the office, you'd like to buy a consumer good. Nothing fancy, just something made at a textile mill, or perhaps some sort of manufactured good.
Assuming that you value the time you spend at work and want to get the most value for your dollars, why would you pay extra to have that product put together by adult breadwinners trying to raise families in America, when you could have it manufactured much more cheaply by people in other countries with simpler needs?
Now switch things around a bit. Suppose you're an American worker trying to raise a family. When you look at all the inexpensive consumer goods available to you, made by people who are no more skilled than yourself, what makes you think you deserve so much more money than them for doing the same thing?
Your American birthright is not the right to be overpaid. It's the opportunity to be as productive as possible. And if think you can squander that opportunity by doing third-world-style factory jobs while making a new world salary, then I'm happy to inform you that globalization will prove you wrong.
If your job can be done by Asian twelve-year-olds, then honestly: What does that say about you?