Even not newbies do the same thing because of lack of patience thinking that bitcoin might fall too much, so sell at least it will minimize the damage but the time they sold, price starting to increase. It not just happen once or twice. Many of us do the same thing imo.

Holding is really helpful and profitable in the long run but many choose to day trade or so and took the risk for higher gains that's why fomo is really a thing to them.