We saw a couple of mini crashes at 10 and 11k. When it hit 7k and 8k, it's normal for people to look toward that next milestone, and say "I'll sell at 10k." And then they do sell at 10k, causing a mini flood of supply, dropping price. We will probably see just as big or bigger "crashes" at 15 and 20k, with plenty of mini crashes at each 1k increment. The long term hodlers will win out in pure earnings. But eventually, you will have to sell or else you've got tons of essentially non-liquid assets. Nothing wrong with that, except for the fact that a bitcoin isn't like other nonliquid assets like land or houses... a bitcoin is worth nothing until it's sold. Sure you can buy some things with them, but this is an odd gray area. Is a bitcoin a currency or a security? As Trog said above, it would seem that spending would be crazy. But at the same time, once again, it has to be sold or spent to hold any value at all. Personally, I'm not much of a gambler. So I will take my small wins when I can. As long as the hodlers hodl, Bitcoin will hold its value. At the point that everyone decides to sell... game over. And we've already seen these mini crashes happen within minutes. If you hold all your bitcoin, watching it skyrocket, waiting for it to hit the moon... You're literally going to have minutes to get off the boat before it's sunk. It doesn't matter if it hits 50k or 100k or higher... If the big crash happens, it will be worth nothing in minutes.
The other side to that coin (pun intended) is... a smart person with a little taste for risk might start buying at that point... which drives the value back up. THAT is the only thing keeping Bitcoin afloat. Joe decides to sell, value drops. Jim sees the drop and a chance to get some cheap bitcoin and buys, driving price back up. The only question is how much faith people have in how far it can go.