Selling all of it is not ideal and it makes it look as if you don't understand the meaning of investment since investment should always be running overtime no matter the number of years be it 20- 30 years and above if there's someone to handle it carefully to maintain the investment so that it can keep on yielding profits overtime and you will always be taking little profits overtime that wouldn't affect the continuity and progress of the investment.
What is the need of taking profits overtime? what will you be using the profits to do? those are the questions and projecting 20-30 years will depend on the age of the hodler and if they have also reach their target of accumulation. The only time i can consider to take profits from my investment is after i must have accumulated to my satisfaction and have made a lot of profits which i know that if a take the profits i will invest it on something productive but taking profits and still keep it in Fiats or some stablecoins will make no sense at all so before intending to take profits you should be able to have a concrete plan of what to do with the profits you have gotten from your investments.
When people say accumulate Bitcoin to the point they feel they are satisfied even myself I use to reason it atimes because I feel there is an extent someone will reach in his or her accumulation it will be like, they should not stop investing because of the potential of Bitcoin what it hold In the future. I doubt if anyone will sell off their Bitcoin investment if they don't have anything meaningful to do with the money and one of the essence of us investing is to also enjoy our profit whenever we have worked some miles to achieve a great height in this investment, because what is the need of investing without selling some when our portfolio is so huge, we are suppose to enjoy our investment and at same time keep holding.