You don't need everyone to leave, just a relentlessly growing percentage. At some point the system starts to crack, and either they relent or it breaks.

In the USA, there is the fundamental notion of "consent of the governed" - if enough people won't submit, the government cannot function.

That's true anywhere, and it's what governments of all stripes worry about and steer. Western ones do it with a bit more finesse, but there's little fundamental difference. It's why Chomsky talks about 'manufacturing consent', and why marketing is an important field for Western governments, as covered in some detail by Adam Curtis. The UK government even have a unit dedicated to 'nudge theory'.

The US government makes it very hard to leave, no finesse involved. To renounce your U.S. citizenship, you have to pay a fee of over $2000, pay huge "exit taxes", and provide six years of tax compliance proof to the IRS. http://money.cnn.com/2014/12/10/pf/taxes/expat-passport-citi...

When it comes to capital China is actively preventing people with money from leaving; and even putting pressure on family members of people who have left in order bring them and, more importantly, their money back.

Well, in the cases I have heard of the money was stolen from the Chinese people so it seems understandable that they want it back.

Also, Chinese are not prevented from leaving the country, que the opposite. Enormous efforts have been spent in sending a lot of student abroad and bringing foreign teachers in (I have been one of them). The thing is for most people here not being able to Facebook is of minor importance compared to access to cheap and good food, secure cities and an environment where they don't feel people look down on them. So, many Chinese students come back to China after abroad studies, despite all the problems in China, and amongst them GFW is the last important.