The particular reason why cryptocurrency markets fall quickly and rise slowly is due to the highly psychological nature and collective behavior in these markets. When a sudden drop occurs, many investors rush to sell their holdings for fear of big losses, which puts tremendous pressure on the prices. Conversely, when prices start to rise, investors hesitate to enter quickly due to fear of repeating the same negative scenario (i.e. fear of bubbles or sudden decline), which leads to a slow increase in demand.
Also, given the limited number of major financial institutions that quickly enter and exit the market, and the large trading volume that can be caused by some major players, we find that market movements are often sharp in both directions.