So there are only
BTC1.8k new BTC mined daily. Volume wise we got about:
BTC4k @ Bitfinex USD/BTC
BTC4k @ Btc-e USD/BTC
BTC3k @ Stamp USD/BTC
BTC3k @ Coinbase USD/BTC
BTC3k @ Kraken EUR/BTC
BTC1.8k daily Gemini auction
BTC1k @ LocalBTC USD/BTC
or about
BTC20k/day volume from somewhat believable sources
+
BTC21MM CNY/BTC
and that's with a stable price in last 3months. Where is the volume coming from?

can't be same people selling to themselves just to pay exchange fees
Read that thread and most of your questions will be answered. At first I would not believe that was happening but it is.