It seems that your life experience is limited ...

Many Chinese came abroad to study in a unpopular field, such as Physics, not because they like it or have great career potential. They took it because only those odd areas will offer them a scholarship. When they graduate, they often find themselves stuck because there is zero demand in the job market for a Physics PhD. Many continued onto post doc - slaves for professors. Others take a new degree such as computer, finance, biology, etc, so that they can switch to a profession that leads to more job opportunities. It's all about survival in a market economy. There's nothing wrong for a PhD to do a MS job with MS pay, as long as the job is bringing home money. Or you can keep your PhD pride and receive welfare instead from the government.