There are many factors that affect the volatility of cryptocurrencies, such as supply and demand, regulation, speculation, innovation and market sentiment. Some possible ways to reduce the volatility of cryptocurrencies are:
Investing in stablecoins, which are cryptocurrencies that are pegged to a stable asset like fiat currency or gold.
Diversifying your portfolio with different types of cryptocurrencies and other assets.
Holding your cryptocurrencies for the long term and avoiding panic selling or buying