I haven’t met any Chinese Christians, so you have me there. But the stories I’ve read by people who have tell me that these are highly persecuted people, quite devout. I doubt they are in it for “fun”. There was even a PBS special on the growing Chinese Christian church.
You are right about the persecution. Christians can expect regular visits from the local state security apparatus and there isn’t any warrant system. You cannot say no. They cannot proselytize legally and they’re fairly well monitored. My experience with Asian Christians has lead me to believe that many are attracted to the Western prestige of it all. I don’t mean to condemn them all and there are some amazing stories out of N Korea of real Christian martyrs. I believe opposition is very healthy for Christians. When life is too easy, so is Christianity.