I'm skeptical about comparing zero fee volume to non-zero fee volume.
To be clear: for short to mid term trading purposes, I absolutely don't doubt the relevance of CNY volume.
But for the longer term view of market volume, in my opinion, the "costly" volume of the three big USD exchanges is a good measure of how much money is "flowing into the market". (Sidenote: I really need to include Coinbase from now on)
That said, I know just discarding CNY (or permanently zero-fee USD) volume is not ideal. I have been trying to come up with ways to 'discount' the Chinese volume by some factor to make it comparable, but nothing ever really came out of it that looked satisfying to me.
Is there a relation between exchange volume and the amount of money coming into the system (or being drained from it)? Volume is generally up when the price is changing, up or down; and that may be cause and effect at the same time. But figuring ot the net input money flow seems to be a complicated computation at least...
I would think that, in China, money is steadily leaving the system: Chinese traders seem to be gradually selling and taking their cash out of the exchanges. This feeling is not based on the exchange volumes, but simply becuse of the decay of the China bubble (which seems to be too fast to be due to miner dumping alone). The rest of the world should still be a net buyer, but there is no data, really, and apparently it can barely absorb what the Chinese and the miners are selling.
There is no "money" entering nor leaving the bitcoin system. Bitcoin is money, so is USD, CNY etc. What happens is that
value moves from one money system to another. When the revaluation of money system is not the same in all actors' minds, there has to be trades. If all actors at the same time and to the same degree change their valuations, there need not be many trades.
Well, I disagree with that assertion.
Except for the chosen few that already (completely and honestly) think of profits in this market in terms of this market's underlying asset, the most common measure of profits (or losses) is in terms of your national fiat currency of choice.
Practically, this means you might withdraw USD profits from an exchange in case you feel like "cashing out", or, if you have money to spare, and feel the price is right, you "cash in" by wiring money into an exchange. This will either remove USD from or add USD to the market.
My claim that some types of trading volume are indicative of this flow in and out of the exchanges is obviously up for debate, but questioning the above process itself I find rather silly. Price per coin is not only determined, on the demand side, by what USD holders on the exchanges are willing to pay per coin, but also by
how USD balances on the exchanges are changing over time. If you don't want to call this process "money entering or leaving", fine, but I'd say you're semantics lawyering now, not really saying anything descriptively interesting.