Because there is more to life that what you are told to believe. Freedom, choice, liberty, all matter more than GDP.
All totalitarian societies are destroyed. The USSR thought it was invincible too, in the end, the resentment within it and it's own mistakes led to it's downfall. That downfall would not have happened had the people had the freedom to express a different opinion than the states, it might have seen it's own flaws and weaknesses and amended them. Instead it curbed pluralism and bought about it's downfall.
You and I won't live to see this day, this is China's time, where it will rise and rise, for maybe hundreds of years it will rise, but totalitarianism cannot survive forever.
Western society is quite totaliarian too, but they create the perception of freedom. This false perception is essential in controlling the people, by letting them think they are the masters of their own destiny.
You deny the uighur people the right to worship their religion. If you truly feel their god is false, why do you fear their worship of a false diety? It's because your society is totalitarian. It cannot tolerate a difference of opinion, let alone a different religion. Your strength is through blind and total obedience.