It's not that big in China, necessarily. The reason people assume it's big is because the large Chinese exchanges offer fee-less trading, whereas the Western exchanges usually charge 0.2% or so. This causes all the traders to move to e.g. BTC China, and their volume to be 50x that of the US exchanges.

Some people interpret this as Chinese people buying bitcoins, but if you look at the order depth of the Chinese exchanges, it's clear that the USD Bitcoin market is much more liquid (by at least an order of magnitude), and the Chinese exchanges may just be used primarily for cheap speculation/day trading.

Personally, I think the Chinese market is insignificant compared to the USD, and that the PBOC shouldn't have any effect on the USD price, so I've been buying call options throughout the crash.