A crash from $266 to 50 is nothing (1/5). A crash from $32 to $2 is nothing (1/16). That's volatility.
A 1/10,000 crash... Well, thats something. That's "a ponzi" that hugely rewards the first in and first out and leave holding the bag everyone else. But still, money it's not infinite even if it seems to be, the burning has to stop at some point... BTC market will always be manipulated as all the markets are, including and especially the commodities ones (prominently gold and silver), but the more BTC grows, the more expensive it becomes to effectively control it. So, this may be an obvious attack to BTC (manipulation), but an expensive one that has an uncertain outcome. I'm also convinced that BTC would survive.
I assume crashing would mean dumping a lot of coins. So they'd buy all they can get, which drives the price higher and then they dump. But selling coins needs two parties - a seller and a buyer. The after-crash price is determined by demand. What I want to say: I don't think they could ever bring it down to 1/10000 or something, because people will buy in and I assume the ratio between high and low of the after crash (i.e. 1/5, 1/16 you mentioned above) will shrink proportional to the gain before the crash.
Nevertheless. Market manipulation and such would conflict with Bitcoin as stable currency, so their goal to undermine a Bitcoin mass adaption is met at first, but just imagine what could be done with the free money they gave away due to that process to those who want a new system.
I think using the media to create an negative image is a better attack vector, as this would decrese the demand of those who listen to it. Also regulation and attacking the interface between fiat and Bitcoin are to name. But the more they manipulate and restrict, the less people will be satisfied with their behavior..
All in all, I'd say Bitcoin will rise and prevail. And that's why we are here, right?*
*At least this is my opinion and perception.
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