The end of a bull run is usually caused by a core factor: the depletion of funds. This situation occurs when market participants are generally getting on board, available funds are exhausted, and investors begin to yearn for future returns.

Looking back at the bull run of 2021, we can see a vivid picture: investors not only disregarded taking profits but continued to add positions at high levels. Even with a small amount of cash on hand, they felt that not investing was a waste. New market entrants were eager to buy in regardless of price fluctuations, even going so far as to borrow or use credit cards to purchase cryptocurrencies, completely ignoring the potential risks.

During that period, the market widely believed that cryptocurrencies only go up and never down, even forming a consensus that Bitcoin would reach $100,000. Even when the market experienced a pullback, most people still firmly believed that the bull run had not yet ended.

However, when market participants have fully invested their funds and even exhausted their credit lines, the market begins to lose upward momentum. Those investors who took profits and exited in the early stages, having already realized significant gains (some even achieving a hundredfold return), are also unlikely to get on board again.

The stagnation of this capital flow ultimately led to the end of the bull run. Understanding this mechanism is crucial for investors, as it reminds us to always pay attention to the market's capital situation, maintain rational judgment, and avoid making impulsive decisions driven by emotions and herd mentality.