It makes sense if you don't actually believe there is a sound reason for bitcoins to be worth $122 right now. If you think this crazy price curve actually makes sense, then, by all means, hang onto your bitcoins because they're just going to go up, up, up. One does have to wonder what exactly you think has fundamentally changed about bitcoins in the past two months to make their value skyrocket, but maybe you have some insight I don't (honestly -- I don't mean to snark. I'm not a believer, but if this is real, more power to you). On the other hand, if you notice anything distinctly bubble-like about the sudden hype and soaring price, it is pretty obvious that at the top of a bubble, things are overvalued, and that if you are holding onto something you know is overvalued, you should sell the hell out of it and buy it back when it is under- or right-valued.