Plus, China's growth to this day is built on the back of foreign, primarily American, consumption. If they ever beat us too badly, they go down with us.
They'd need to find alternate consumer markets to alleviate this, and what are their options? Domestic is out, China hasn't managed to create a domestic consumer market with their current demographics, which are only getting worse as their baby bust deepens.
Europe? Similar demographic issues, simply not enough consumption to replace the US and greater economic protectionism.
The 3rd world? Maybe, but first you have to develop it, and even if you could manage that they have nationalist impulses of their own. You think India is going to willingly offshore their industry to China on the scale of the US?
The American system for all its many flaws is extremely dynamic. Trump and his policies are mostly bad adaptations, but they are attempts at adaptation, and the attempts aren't going to stop. The US has changed radically in the last 10 years; there's no reason it can't change just as radically in the next 10.
Why must the consumption be exported?
Why can't they build for themselves?
Because that would lead to mass unemployment and deindustrialization, as China lacks the wealth among the lower classes and the demographics to consume everything that it produces.
Wealth is made.
Yes, in China's case through mass exports. What you're suggesting is North Korean Juche. Turning China into a larger North Korea will not increase its prosperity.
Yes, currently.
But you have made no argument for why that must continue, only presented that is the status quo.
China is huge and I am simply wondering, why does it need to export? Except for oil, it has pretty much any resource needed to sustain a high technology economy.
Please, there are no similarities between North Korea and China.
The argument is self-evident. Businesses need sales to make money. By refusing to allow them to export, you artificially limit the sales they are able to make. Businesses with fewer sales make less money, businesses that make less money employ fewer people. People without jobs tend to have problems securing food, water, and shelter, and start to get angry enough to topple governments.
Sometimes they win, sometimes the government just kills all the angry people, and you end up like North Korea or Russia under Stalin (or China under Mao).
There's also the fact that China is an aging population and is structurally incapable of having enough children to create a self-sufficient consumer economy, unless they suddenly develope a love of immigrants.