Why does the US stock market keep having record years while the population doesn't seem to benefit, whereas the opposite is happening in China? Isn't that a failure of US capitalism?
What do you mean why?
This memory stock popping on IPO has nothing to do with how well/bad capitalism provides in the USA. This is entirely about Chinese investors speculating on this company's ability to grow and undercut some Samsung, SK Hynix, Micron. Nobody knows on IPO day if a company will grow into the expectations of the investors.
And China's population mostly invested in Evergrande real estate, not stocks. Lots of workers in the US are at least invested in the stock market via their 401k/IRA, but the same isn't true of Chinese workers.
Also worth reiterating that most US stocks aren't doing great. The top 10 by market cap keep dragging the indexes into growth, but success is heavily biased towards the monster caps.
Is the latter part actually true in this decade or just "face"?
imo, every form of country order has a tipping point from where it starts deteriorating at record speed - cannot tell exactly what comes after ultimate capitalism but I think it's hitting peak points
It's not a failure, that's just how capitalism works.
The population in china is falling off a cliff....low birth rates, collapsing property prices (the main vehicle for personal investment), slowing ecconomy.