The panic in the sale will bring harm, so try to stay relaxed in the face of any severe situation, because it will return to normal just take time to recover as before
It will bring harm to them because they are the one that decided to sell their bitcoins. Because they think that their profit is already enough but they are the ones that are giving some doubts about bitcoin's pump. Instead of making bitcoin pump, when they are doing panic selling they are not helping anymore.
But if the price of bitcoins exceeds their entry price and if its giving them huge profits then I don't think its smart to hold their coins at that stage and instead they should be sold to get huge profits from it as if you will never sell your coins then you will never make profits from it.