The decision to sell during a price dump isn't as simple as a panic and sell. A lot is dependent what price you bought your coins at, when price it is before the dump started and also what price it is at presently.
If you are able to get it at a great lower price, then there is nothing wrong with selling part of your cryptocurrency holdings if you fear that a dump is about to happen or is happening, it is wrong however to hold unto coins you bug at a ridiculously high price due to FOMO because you want to recoup tge prices that you paid for such coins