Well, before Mt. Gox, bitcoins were about $80/coin. Its initial upward trajectory from $100 seems almost assuredly Mt. Gox pumping up the value. Who knows why Karpeles did it, but it probably had some kind of avalanche effect which he had no idea would peak at $1,100/coin. Since then, the price has been slowly resetting to pre-Mt. Gox levels.
By pre-Mt. Gox," I of course mean "pre-manipulation."
That's my working theory. If true, the fact that bitcoin has slowly been resetting to pre-manipulated levels would be the first example of the market ever being rational that I'm aware of. (Besides, you know, the fact that insider manipulation of the market was successful in increasing the price, which is rational by definition. Just not in an open happy way that people normally associate with the phrase "market rationality.")
But there are all kinds of problems with that theory. It's something so simple that you want to believe it's true. There's no reason why someone else wouldn't also be trying to manipulate the market now, like BTC-e. There's a financial incentive to try to pump up the price, so why is it continuing to fall, or rather why are current attempts at manipulation failing? Could it really be true that Mt. Gox was the only manipulator ever to have had a significant effect on the price? Seems unlikely.
Maybe the true explanation is that there was all this pent-up unknown hype for bitcoin, which Karpeles' manipulation unleashed on the world like a crack that broke a dam, either to his joy at skyrocking the price or his shock and horror at skyrocking the price, and now everyone's resetting back to pre-hype levels.
I still think bitcoin has value. Even after being used and abused, and dragged through a meatgrinder that shred away every ounce of my bitcoin fanboyism. There is true value there, and that is its ability to get money from you to me in seconds, and then my ability to sell those coins on an exchange for fiat that's deposited into my bank account within just a couple days. In that scenario, it doesn't even matter what bitcoin's current price is. All that matters is that the exchange honors the agreement at the time the coins were sold, because the flow is that the coins go from you to me to being sold on an exchange/middleman within a few minutes. So the current price of bitcoin is whatever it is, and I'm still paid however much I was expecting from you.
And it seems like a solid upward trajectory could even be built on that foundation.
But it's going to take patience and time.