Market is very unpredictable, you will just lose money if you sold your crypto at a low price because you think it will dump more in the next coming days.
Yes you are right because Bitcoin is dumping many are selling at low prices. They may think that bitcoin will be more dumping in front of it so they are now selling at a low price. They may not know that Bitcoin had been dumping in 2018 and it's okay again. Now maybe Bitcoin has been dumping and it's okay in the future if they sell it, they can get a good profit.