When the market become good then take your profit because market is unpredictable and when you have taken your profit and the market again downs then there is no need to be worried because you have taken your profit from it.
That's common advice for short-term traders, but may be meaningless to long-term holders.
Traders need to build their portfolio that way and they will create regular trading cycles for the same purpose. If they can do it consistently, especially if they have expertise, then they can build a bigger portfolio.
Person will face loss only if he is not in a condition to wait more, people not always face loss due to impatience but sometimes people needs money for something else which is very important of life therefore they sell their bitcoin with loss so its not a fault but its a way of fulfilment of life expenses.
My advice, have a spare budget instead of putting 100% of your budget on trading and investing.
You must have these alternatives if you don't want your trading and investment plans to be disrupted, so consider them wisely before you do.