Bitcoin is a digital asset that appreciates in price over time, and when your investment has grown or appreciated in value, the investor has to take profit, and this same idea is applicable to bitcoin investment too.
In my own understanding, bitcoin is a digital asset that rewards investors on the long run, which means investors should not sell during bear market, and out of impatience.
More also, I understand this statement to mean that , investors should always have Bitcoin in their portfolio or possession, and even when you sell after making profit on the long run, you still need to reinvest more especially during bear market or Bitcoin dip.
Your comment is leading directly to trading. An investor never sees a small profit and sells the investment before the expiry of the period. An investor has a long term goal like 4 to 10 years or more. As you said, sell when the price increases or your investment becomes profitable, that is always what a trader does.
It is never a right decision for a person to sell the entire amount of his holding. When the period is over, you can withdraw some amount and enjoy it or you can withdraw the amount you need. But withdrawing the entire amount will never be a right decision.