They don’t need bitcoin for the first stream, just for the second. Besides, there is plenty of excess capital floating around in china anyways, they don’t need many initial investment from the outside.
The outflow of the capital from China via bitcoin must definitely be larger than inflow. And those who transfer wealth from China via bitcoin are keenly interested in bitcoin growing as much as possible without crashing. They likely have bought a lot for a much lower price, and want to cash out in the West, at least partially, without trouble.
* Chinese energy producers and miners get cash into China from bitcoins they create and sell.
* Chinese (early) buyers of bitcoin sell their coins in the West for cash stored in Western banks, or turned into other Western assets.
I suppose the second stream is wider, but the first is not to be neglected, too.