They go crazy because a lot of people have made a great deal of money just this past year so they want in on it. They see it as a fast way to make a huge profit and not as a long term investment.
it is true that Cryptocurrency is making us more crazy in just last year, more and more people can not expected that bitcoin has made the entire market risen in just a very short time, brought huge profit to investors who dares to invest in bitcoin earliest, more and more people reallized cryptocurrencies can open a new future for all of us to enter a world without paper money anymore but digital currencies, making the world a better place.