It's expecting bitcoin to double and triple that got us in this situation in the first place. Too many people come in wanting the market to go nuts so they can make a quick buck. So the market goes nuts because of the influx of money.
The smart investors start taking their profits and the weak investors get scared at the smallest correction and jump ship. This makes the small dip a larger on which scares more people, etc, etc.
If we can keep the feeding frenzy at bay for a while we can probably see good steady sustainable growth.