Most buyers of bitcoin early on sold when certain gains were realized and then were replaced by other buyers or joined other buyers later at a higher price. The few who have large holdings from the early period and have held on and who now might like to start to lock in gains will trigger a precipitous decline if they try to do much selling since the total market cap of bitcoin is so small. Such a decline would lead to a cascade of further declines as those who bought at higher values see losses pile up. Bitcoin also has competition now and the competition is winning in the game of who can achieve the fabulous short-term gains. Rival Ethereum is up 3601% for 2017 compared to Bitcoin’s 136%, but if you have purchased Ethereum at $13 when if flash-crashed to that level from $296 in a matter of minutes last Wednesday, then you would have earned 2200% in a matter of minutes when it jumped back up. As things stand Bitcoin is down by about 16.6% since last Wednesday. The total value of bitcoin in the world is extremely small. A number of super-rich individuals could buy every bitcoin tomorrow and not use up 10% of their wealth. Or, they could just buy 5% of all the bitcoin in the world for what to them would be beer money and then as soon as they figure out how to short it when/if it ever achieves real market presence; they could just sell all their holdings crashing the price and then use their gains on the short to rinse and repeat. So much for stability.