Someone just moved 6.5% of all bitcoins in existence. I don't think that any person or company has control over anywhere near 6.5% of the world's dollar market.
Someone could own that much of the dollar market, but yes this have more to do with there being much more speculators than users of bitcoin who control the majority of the fund. If everyone on the planet only trade fiat currency rather than using it as a currency, you're going to get a lot of fluctuations too.