I don't think it's because they were greedy that they made that mistake, but because they don't have the knowledge and experience of trading, maybe they think about losing assets and panic too much when they see the price of the coin drop. It seems that almost all members of this forum have made such a mistake. I myself have also experienced such an incident.
Basically, everyone is not taught to panic, so if you ever feel panic about something that is happening in the market, then in the future what you have to add is patience in dealing with every situation that is befalling you, that's all.