Most people are here for the profit. So when the price goes up, the sell and take the profit. When it goes down, they reinvest.
Yes, it is a basic principle of trading and investing. Buy low and sell high, it is a way to make profits regardless of the time frame they adopt in trading. Regarding investment, it is hoped that it will be for a longer period of time, for example 2-5 years and selling the three targets is expected to have been achieved.
Price volatility should be utilized by traders, especially for those who like trading strategies such as scalping or like that. But if they are investors who expect returns in the long term, then of course buying on the dips and accumulation is the most advisable.