Bitcoins are not bubbles as some people often think bitcoins are like digital coins and are likened to gold even more than gold because of some of their properties such as swapping.
You don't understand even good currencies and assets can bubble once in a while, this happened to gold in the past and I don't think there is a person here that can deny that gold is a great currency, so even if bitcoin is one of the best currencies in the planet that doesn't mean that too much money cannot be invested in it, and we saw that at the end of December when simply too much money came to the market.