Even then the recent drop was basically just a big trading opportunity-- the rumors kept building and once an exchange said they were going to shut down, all the whales piled in at once... to kill the price and take profits and drive out the weak hands.
And then when the other exchanges were clearly going to shut down and all the shorts had been built up, these same whales piled in at once again to get coins at a lower price.
Thats why the move is so dramatic and so quick.
I don't think this was collusion. I don't think this was coordinated or communicated or even intentional-- it was just an obvious trade and so a bunch of people jumped on it.
One thing about BTC is that it is a free market, and that means you don't have market makers who act as stops on price movements (or trading hours, LOL!) and so things are very different there.
This is why the general advice is HODL. Just buy bitcoin using dollar cost averaging, don't risk too much and hold it. Timing the market is a PITA, and I'm convinced impossible on the micro. On the macro scale, though, HODL is the best strategy.
PS; here by HODL I mean "hold on for dear life". Don't get shaken out of your coins by roller coaster weeks like this one.