Most people will tend to sell their currency out of fear during a market downturn. If you are holding altcoins, you should stop the loss in time to reduce the risk. It is better to lose a small amount than to lose all your funds. Be patient when holding Bitcoin, trusting that the market will rebound and the gains will continue to be reaped.
That's the thing with most altcoins holders, they tend to think that holding altcoins is significant but if you look at what they're holding then it's too late for them to keep on holding it.
What's wrong is when they've found it out too late and then they start to think of cutting loss. Well, 5%, 10% or 20% are still good but if it goes like more than that then it's really quite late for them to sell at losses. But I still see some few success stories that they've made the decision to sell at losses even it's too late already but then recovers with the coin that they've bought.