Think about this for a second.
A very large, well financed mining company could do the following:
- Hoard many mined coins for a while.
- Deploy a massive amount of new hardware, which pushes the difficulty up substantially.
- Dump many hoarded coins on the market at once and push the price of BTC down.
- Laugh all the way to the bank as many smaller, less financially secure competitors fold, thus leaving a bigger slice of the BTC mining pie to themselves.
KNC and BitFury both likely have enough resources to pull off the above scenario and drive many competitors out of business.
Market manipulation comes at a price.
That price has to be paid by the manipulator alone.
The profit, though, does never go to the manipulator in its entirety.
That's why, in a nutshell, market manipulation is not profitable.