When we start winning we get anxious about loosing our gains .we close trades prematurely to capture the profits before the price starts to drop again.wereas we should be holding on to it and closing appropriately to maximize the profit.
In fact, there will never be a trader who can be right when selling at a high price, that's why they carry out analysis and what must be obeyed is to follow what has been analyzed, if it turns out that when they have sold the price still continues to rise, there should be no regrets because the trader can open another position at another time which is different from also carrying out analysis first.
Conversely,when we start loosing we hold on to the losing position longer in the hope it will turn upward at some point.we have the irrational beleif that we will reduce or wipe out the lose without proper re-analysis.
The mistake is because they don't want to cut losses because they think the price will still rise and keep waiting for the price to rise. If trading on Bitcoin then it's just a matter of time, but if on altcoins then the trader must be prepared to see the price of the coin never rise or reach the last price he bought it.