The rise in Bitcoin's price, in its current size, has all the alarming signs that it may be a BUBBLE. What is a "bubble" or balloon in economic / financial terms?
"Bubble" is an economic / financial cycle that is characterized by a quick rise in the price of the asset (in this case Bitcoin) and ending with just as drastic drop in price or blast. The balloon is created when the asset price is "trumped" unreasonably, unfounded in the "fundamentals" of the investment decision. In these cases the price is "blurred" by the huge demand for the asset, motivated only by huge enthusiasm (mania) to win fast and easy.
When does bubble break? At the moment when the demand falls, when no one wants to buy the asset (in this case bitcoin) at overcrowded prices (so the market suffers), and when the massive sale of the asset begins!
According to Krugman (Nobel Laureate), the situation with Bitcoin is a typical bubble, "Bitcoin has not demonstrated in any case that much helps us in economic transactions." Everyone who today buy Bitcoin does not buy it to use it, but they buy it with the idea to win, because its price is rising, and so. No one understands what he is investing, the asset is "mystic", is not controlled by anyone and there is no institution that "guarantees" the asset.