Because there are no limits of changes within a day like stock market. There is no circuit breaker for the market to stop panic. Crypto market now is a free one, free of limits, free of circuit breakers. Price can move up or down without any limits.

Price in turn changes fastly because of price manipulation and news. People invest in crypto but most of them don't know what is bitcoin, and what are waiting for them in crypto market. Then when bad news come they panicly sell and good news release they buy with joy of FOMO. They should do opposite as the saying goes "Buy the rumors, sell the news".