First of all Bitcoin is not a bubble but it has some rules how it's functioning. Looking at such conments here on forum it's easy to conclude that many users don't have a clue what is Bitcoin and how it's functioning, what are the basic characteristics. And that is really sad. They only motive is obviously only greed and when they are unable to fill that everyone else is fault and of course Bitcoin at first place. This shows how education about Bitcoin and cryptocurrencies in general is deeply needed.
Bitcoin itself is not a bubble. There's no disputing that. But the boom and bust cycles are similar to those which people would associate with a bubble. A bubble does not have to begin and end at 0.