People in China, at least those millions people who are able to cross the Great Firewall, know that democracy is generally good, but they also know that a strong central government can also be useful for certain circumstances. Most westerners and HongKongers on Hacker news have a very extreme political view, you just believe "democracy is good"(TM), protesting against the evil Chinese government is good. But can you take a closer look at what is really happening in HK and then decide what you believe?
BTW, I'm neither pro-protester nor pro-police, I think the protest is a result of economic regression in HK. You could also check my comment and posting history to see that I'm not a 五毛党.
Why do people support bad governments? I recommend reading about Havel's greengrocer.
Obviously the Chinese government is capable of doing some things right or it would, as you say, collapse.