What is your views and conditions at that time?
If you manage to sell at the right time, it is very enjoyable to invest. But if the prices start to drop after you buy, you have to wait for a long time. Many coins will do ath again, I have no doubt about it. But it's hard to know when they'll be able to do it.
That's why selling when prices rise can be a very good strategy
All this has a presumption depending on the type of personality of the person, if the person is of a trading operator style, a trader usually establishes a Stop Loss and a "Take Profit" according to it when he touches the stop there is no more nothing to do but assume the loss, but in case you manage to sell and take profits it is ideal, you should not regret taking profits, it is what you always want, in case of selling at an ATH it is the idea, it does not matter that a correction comes later, you just have to have the conviction to always come out on top.