Nobody really knows it. Harvard professor also doesn't know. Bitcoin as well as whole market goes down because of fundamental reasons. Hype from ICOs in 2017 is gone and there aren't so much positive these days about cryptocurrency. Big players need to fill their own bags full. It will take some time, may be it will take long who knows. But also there are no fundamental reasons for cryptocurrency to die. It will rise again. Believers will benefit from it but most people will sell at lows.