Because the price change depends on how active the trading volumes is. Due to the fact that crypto is not regulated by anyone, it turns out that the price is easy to manage, especially if the trading volumes are small.
Agreed, the trading volume happening through different exchanges play a big role with the price of cryptocurrencies. The constant change in the market happens, and it is one among the property every cryptocurrency holds. There were few exceptions holding stable value. These price changes were the one that contribute good to the different earning access through trading and other forms.