Well if bitcoin is driven by greed and insanity I don't think it will succeed.
I, on the other hand, think that that is the best guarantee for something to succeed !
It is the most powerfull drive on earth.
Remember Nasdaq's Bernard Madoff? He conveyed a 30 year ponzi-scheme worth billions. He declared profits out of thin air. Profits that did not exist. And when people tried to cash them in - turned out their investments werent real and they had nothing.
What will happen if say BTC reaches 10 grand/btc? Everyone will start selling. However, at some point exchanges will stop, because supply will be astounding and there will be no more demand. So there goes open market for bitcoins.
Those price fluctuations are possible only because very few people have large amounts of bitcoin.