The question itself is the answer
PANIC.
Everyone knows cryptocurrency market is highly volatile and risky.
And most of the people do emotional trading.
They sell when it is crashing. And suffer from the loss. They panic and sell in the loss.
What is the point in selling at low?
One must wait for the market to turn green and bullish.
The way to stop the panic is to not engage in panic-inducing activities such as day trading.
It is like the old joke; a man goes to the doctor and says my arm hurts when I put it overhead.
The doctor says dont put your arm overhead

If you are in need of urgent money than selling is OKAY but for profit,
HODL is the best.
indeed the cryptocurrency market is volatile and risky. and there is no point in selling in a low state. because selling in a low state causes a loss when buying at a high price. and maybe that's one result of the panic. maybe hold is a great way to do as you suggest. but in my opinion people who sell in low circumstances, in my opinion, maybe they want to do trading activities again and make little profit from the new trade to restore the first loss of capital. by utilizing the existing market wave. because in my opinion, if we just hold, there is no activity we do, and our time becomes useless when the market price does not return to the value of the losses we experience. so in my opinion, it could be that those who sell in a low state, it is their strategy to trade again and that they do not just because of panic.