The Chinese appear to think, collectively, that authoritarianism is better than democracy. They could revolt. The Chinese military is under funded with failing equipment, though they are trying to improve in areas. The sheer size of their military makes it difficult to have common weapons and gear available. 100 million citizens throwing themselves against that machine, would wear it down quickly. They don't do this.

The Chinese had a century or more of bloody civil war recently, within historical terms. They don't like regime change.

They historically were fine under the emperor, who was authoritarian. They are use to autocratic, central government. Unless things get extremely bad, I don't see them thinking that democracy is better than their current stability. If Xi Jinping does a decent job of getting rid of corruption and improving the air quality, I doubt you'll see a revolt even with a depression in China.

Edit: for those downvoting, how about a dialog? Democracy is not a native idea for the Chinese. Their major philosophical systems support a rigid hierarchy, which is not compatible with the democratic norm of anyone can attempt to run for office. They've lost millions to wars before Mao calmed everyone down. Even with Mao's major famine, there wasn't a revolt. 45 million died, and no uprising. If 100k died at the hands of the US government, there would be blood in the streets. Probably true with 1k. The Chinese do not care about authoritarianism.

The military equipment is irrelevant; they are still far more coordinated than the civilians are permitted to be. Suppressing collective action is one of the central goals of authoritarian censorship.

Democracy is no more a native idea for western culture; 250 years ago every state was a monarchy, and political ideologies based in hierarchy still regularly win elections.

I think your notion here is naive. Assuming a majority of people in China is fine with the way the government runs, does not negate the fact that many people are not. In a country of a billion people, we are speaking of millions of people. For this, as a first step, you just need to look at minorities like Uighurs, Tibetians, Mongolians. It does not end there.

Also, you cannot use the word "choice" when no options were ever given. A large chunk of people can be unhappy with how the government operates while still not marching the streets. The world is not binary. People living in China also know that the government went to extreme lengths when it came to ending protests in the past: shooting at their own citizens.

The joy of market processes is that those who like Pepsi more and those who like Coke more can both be satisfied at the same time, unlike the Republican voters of San Francisco or the Democrats of Utah.