It's called a bubble when something is hugely overvalued. Usually this happens when lots of people are so excited about something that they put a lot more money into it than it is really worth. At some point, the market realizes that the actual worth of this thing is really a lot lower and people start selling it off. That's when the bubble pops. The financial crises of 2008 was also a bubble, caused by too many people buying into real estate (facilitated by shady practices of banks). Some people say Bitcoin is in a bubble because the excitement over it is huge and a lot of money is flowing into it. Hope that helps.
This is so true, Only an investor or businessman alike can really understand the value of bitcoins, the only hindrance of this cryptocurrency is that it has no legal basis to many countries that is why it is still being ignored. By the time they will eventually find a way to regulate the used of bitcoins, they will eventually open it to the public and also taxation will be imposed so that they can include it in the computation of the GDP to know how this cryptocurrency affect the economy of a country.