That's the thing with trading, you need to aim for a profit, but be ready for a loss at the same time and that is very tough. You could just sell it all and get out which would make sure that you do not lose when it goes down, but if you do that then how are you going to profit when it goes up?
Sure, when we decide to trade or invest in crypto coins, we must be ready both for profits and the losses. The result of trading or investing will be always those 2 things (profits or the losses). When we sell your coins, it depends on our goals. In the ideal condition, we must sell for profits. When people sell for losses, it is only for an urgent situation. That's why always choose safe coins and use safe money, so we don't need to experience urgent situation.
You could put all your money into it, and hope that it goes up and that is how you profit, but how would you protect yourself when it goes down? So you need to find a perfect place and method where you can profit when it goes up but be ready not to lose much when it goes down. Stop loss is a great method for this, you end up holding, but if it goes down then you are going to be basically holding it carefully and getting out when it goes down thanks to your stop loss.
It is always not recommended to put all the money. Only use safe money for trading or investment, use an excess money only!!
We must remember that trading or investing in crypto is high risk, specifically for altcoins. So, don't try to gamble with our luck by spending all the money!
For people who understand how to deal with the risks, they must set a stop loss. It is the way to prevent a huge drop in crypto price. But not everyone set a stop loss, I have friends that never set a stop loss when they do day trading. They said that it is no need to set a stop loss, it is because they entry and exit just in a single day.