What causes a bitcoin bear market?
There is no single cause.
Bear markets in stocks, commodities, crypto or other markets always share a common narrative of prices and optimism outpacing fundamentals. Bitcoin market cycles are no different in this regard. Every period of speculative mania inevitably exhausts itself, and upward price trends stall then reverse. Specific catalysts for these reversals vary every cycle, including bank failures, regulatory crackdowns, geopolitical unrest, monetary policy changes, and more.