The major cause of the bear market is the historic patterns of Bitcoin's market cycles. Once the long-term bear market had been established, by falling below the 200 Day MA (in March/April), then a 80-95% drop at least to the 200 Week MA was almost inevitable as history shows. Regardless of everyone's false belief that $6k would hold, despite the bearish indicators that highlighted a target of $3k (or lower) from breaking the 8-month descending triangle.
My other argument is that the parabolic rise in December 2017 has led to the parabolic drop this year. The quicker we truly capitulate the better.