According to scientific research, about 4% of the population suffers from depression. But I am sure that this figure is much higher among traders, especially in a bear market. It is during a bear market that any desire to trade disappears if you have not sold your coins at a higher price in a timely manner.
The reason is that greed is very much why this happens. Some people believe profit is easy and they increase the risk that they take so they keep losing. Trading is not for everyone but everyone wants to do trading whether it is clear or not. It is not given to everyone to understand so you have traders that don't know nothing but they don't want to only hodl but they throw in money for trading and they lose. Learning is important for those who want to go into trading otherwise you hodl your coin in your wallet and expect a rise.