Oh heck, Market gains have been "manufactured" since the crash of 87. S&L bailout and market support by the FED ever since. Greenspan was master of "bubble" creation. I cut my baby teeth on Wall Street in 70's. Hard to tell real from fake. I would not hold you breath waiting for belt tightening. I do agree the market is over valued. It was under Clinton and then Under Bush and again under Obama. Basic problem is the FED working very hard to do what is was created to do: protect the rich.
The collapse baby Bush left us was "fixed" not by anything the government did or spent but rather by simple change of an accounting run for banks. One morning they change the requirement for banks to "mark to market" all those bad loans and bam, the market took off. I think is was 10:30 or 11:30. Insolvent banking system was miraculous fixed.
The stock market is NOT the economy although it sure looks like it when you listen to talking heads. Being an old dude, I've seen a lot of economies. Since I came our of college in the early 70's, individual person wages have been going DOWN just about every year same one until Trump came along. When his doing of not, wages start to grow from the bottom up. Hey my income always went up but I am not a "wage earner". Heck the stopped talking about "individual" wages and switched to "family" income to let more people going to work in households cover the truth. There are several reasons for it but fact are facts.
China is it's own story but you seem locked in on a narrative so rather than try, I'll give you direction to look and if you want to figure out what is going on you can. It is not as it is portrayed. You need to go back to Henry Kissing and Tricky ****ie Nixon. Focus on Henry and his beliefs and writings. It is serious geopolitical. It will take work but very interesting.
If not then simple simple math and economics. US has about 350 million people, or "consumers" as far as economics is concern. As you noted, China has many times more "people". We somewhere between 30 to 40 % of world consumption. So we are at most 5% of the world population but equal to say, for simplicity, 40% of its consumption. That means US consumers equal somewhere north of 3 billion consumers or China plus India plus a few extra. That is the power of the America consumer, about 8 to 1. We spend greater percentage per dollar earned than anyone. Without access to the US consumer, China will need a couple more billion people to even try to "overtake" us. That access it totaling within our power. Cut that trade and China collapses under the weight of over capacity and severe damage to it economies of scale. Go back to Henry to find out why we allowed this to happen.
