If we are not a holder, this means that we may be too greedy to expect the price to rise higher and higher again and we can get higher and higher profits again. That is why it is better to set a target price of rising. If we are expecting higher profits again, I will prefer to sell at least 75% of the total amount at the targeted price, and then leave the last to hold.
At least, I can still save the funds to make another trading again and get profits from tradings.

And this is how a panic sell because of the market down and also FUD. Many people do this, being panic when the price suddenly goes down