This is something that should be done as soon as you enter the trade. And the reason is very simple. Most traders tend to fall in love with a coin or with a trade. So, when they are losing, they just say “wait, it will turn back up”, and let it sank ignoring, many of the times, the stop loss they had established in the first place. However, when the trade is going in their favor, they just keep congratulating about it and don’t exit the trade on their initial target price. So, when the coin suddenly starts falling, they get very surprised and not even at this point they think about selling it. They just think that the coin will go back up there again.