It's the progression of countries from agriculture economies to service economies. 1950's US was a manufacturing powerhouse with almost entirely in house supply chains and with heavy public infrastructure drives, not at all unlike China today.

But trust me, all those people working in poor conditions for cheap pay in China will do everything they can to ensure their kids don't work those jobs. And just like the US, that fountain of cheap labor will go away and everyone will want their comfy high paying desk job.