As Bonsaiv points out, this single-stroke, one fell move, would never have the intended effect, if in fact the manipulation were to happen that way. It might result in a momentary flash crash, but then prices would restabilise pretty quickly. Single entities have been discussed of course, with some compelling evidence, especially by this guy from Hackernoon: hackernoon.com/meet-spoofy-how-a-single-entity-dominates-the-price-of-bitcoin-39c711d28eb4 and his other articles.
Spoofy may not be real, but the narrative is interesting and not entirely unscientific (otherwise ignoring the choice of language).
It wasn't not a single-stroke, one fell move. I watched the price go down for two days, and it didn't look like a flash crash by any means. This is the point which I want to emphasize once again. It looked like a deliberate attempt to move the prices down in a consistent and gradual, even frightening manner, allowing more traders to enter the Buy side of the orderbook and then relentlessly eating their orders. It was a very well thought-out scheme, not some frantic effort to close a position at any costs, which is what most flash crashes can be traced to. That's the main reason why I started this thread.
Think about this though, these would-be manipulators would surely not want to kill their golden goose. Even if they brought the price down, it would only be for them to re-enter into long positions. Why make a few billion today when you could be making hundreds of millions for many tomorrows?
I see your point but you may miss a few other factors that may be in operation here. For example, it is sort of common knowledge that when Bitcoin price falls, most altcoins fall even harder, and harder may be a serious underestimation here. So what if would-be manipulators are really trying to move their financial capital from Bitcoin to some other coin like Ethereum or Litecoin? I think in this case they wouldn't care if Bitcoin dies in the process as long as the coin of their choice survives. Also, given the general negative attitude toward Bitcoin recently revealed by the powers that be, it may in fact be worth earning a few billions today because there might not tomorrow at all. What do you think?