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I believe there's no harm in selling some of your investment if it gives you profit already, assuming you don't sell all of them. I believe there's a detailed guide on how to calculate how much you could sell in the past.
Because the main purpose of investment is profit, there is nothing wrong with selling part of the investment for the profit that needs to be taken.
But sometimes there are people who are too confident by not wanting to take a penny of the price they get when the price has shown the target price they want to achieve.
They expect too high and when the price starts to fall and continues to be followed by a prolonged bear market,
there will only be regrets, why not sell some and then buy below.
Setting how much to take profit is also needed, I will also take some profits when the price exceeds my main target,
and surely the profit can be a reserve fund to prepare to buy on the next decline.
But it all depends on how each person's strategy is, some continue to survive and forget their investment for years and when they start to open their investments, huge profits are obtained perfectly, but also the opposite happens.