Patience and self-discipline - two knight-traits for the traders to acquire in order to become the masters of the market, not a prey for it.
Those two are really important traits of a trader but as humans it's hard to have patience and apply self-discipline when you see your positing gaining more green candles.
Some of such traders sell their positions by securing less profit, but if they can apply self-discipline, and have patience then they could literally make more profit by holding.