Modern China was built off the backs of Cheap Manual laborers
China today seems to put bright people into improving manufacturing technology. There are PhD theses from China on electrolytic capacitor free switching power supply designs for LED lightbulbs. US academia would frown on something that practical.
But that's not really unique to China. One can go to the more expensive cities in the western world, and take a look at how the working classes are just surviving. Zero upward mobility, once you're trapped in those jobs - from a professional point of view.
I've had the great displeasure of working minimum wage dead-end jobs, in a major city, and it was the most stressing thing of my life. Poor pay, ever-increasing rents and general living costs, zero job security, close to no prospects of owning your own apartment or home.
You don't really feel like a permanent resident. Just a transient passing through, and when the jig us up, you're out.