Aside from the need for a serious correction after such a crazy run-up this year, I think at least part of it is the South Korean exchange Youbit filing for bankruptcy after being hacked by North Korea.

Edit: If you look at the daily charts, there were also some technical indicators pointing to a significant correction--namely price-MACD and price-volume divergences.  The beginning of November, when the Segwit2x fork was canceled, was the last time there was a price-MACD divergence.  Price dropped about 30-35% during that correction.