That's where you're wrong, unfortunately. Manipulation is real so if they are placing bets against Bitcoin for hundreds of millions they can make their outcome happen by dumping the real Bitcoin. Say a group of 20 hedge funds/or even individuals came together to place a bet against BTC at 20K, they all have $100M shorts on CBOE equalling 2 billion. But before they did that they bought 25M worth of REAL BTC through GDAX, GEMINI, etc. They dump their 500M worth of BTC, win the options trade and then keep placing higher bets which will allow them to manipulate more and more BTC.