They are doing it because of their fear of losing more money ,
They bought it because they think that they could gain a profit from it and they ended up losing more.
People who buy without a proper study about their investment will lose money on selling at low. Because if a person does a proper study before buying then for some unknown reason if prices go down then those people who believe about the product or coins will buy some more at a lower price instead of selling at losses. That's why you need to do a proper research before investing your hard-earned money.