The market is never rational, it's all about future expectation, it's a full speculation, nothing about the present. What happened in 1929 ? 2001 ? 2008 ? In history, there is a bubble every time, bubble is just a wrong expectation. Is it rational that Bitcoin lose 90% in few months ? The market is driven by sentiments, if market where rational, pump and dump because of nothing will not happen, up and down movement should only happen when a news come in, but... it's not like that, so the market is not and will never be rational. If you want a rational market, humans should not be able to buy or sell, only programs which are making decisions with news, because humans are driven by emotions, we love, we hate, we have expectation and hope, nothing rational here. Why do you buy Bitcoin ? Because you think it's the best store of value ? Maybe you are wrong, so, isn't a bubble ? Who knows ? What is rational ? What is not ? Maybe you have right, maybe not. It's all about speculation, isn't ? We are betting isn't ? Maybe Bitcoin will be hacked, maybe it will be shutdown, maybe the US Government will suddenly ban it ? Do you know the future ? So, what is rational ?