Not a bubble, they are already present and growing quite well around the world, so we see the market today is never able to criticize these coins, so they have created an extremely large spider web
Bitcoin is a phenomenon, in a decade has turned into an important currency. Although the beginning of the creation of bitcoin, its value can only buy pizza. But now it is worth thousands of dollars, even in December 2017 the price was almost US $ 20,000. Is this a bubble? I do not think so, but prices are formed because there is supply and demand.