That's a very good point there, and of course selling our bitcoin at once seems to be a wrong method in my opinion. However, I think the best method of selling our holdings probably when we must have reach the status of overaccumulation is by selling some amount which you know is okay for you as an investor, but the amount is not supposed to be more than 30% or in such a way that you won't find it difficult in trying to build back your portfolio that's in my opinion, Instead of selling all our holdings at once. I could imagine how long it will take for an investor to build back his portfolio to it's normal standard, and most of them can decide to give up after they must have Considered the time/ years which they're going to spend in building back the portfolio, because that strong determination which they had when they were still new into bitcoin investment is no longer there.
It is not right to think of selling your holdings until your investment period is over. It is not right to think that you can sell some of your holdings just because you have reached the point of excess savings. When you have gained 2 times the amount of your investment, then you can withdraw some amount and enjoy the profit. But it is not right to withdraw more than 10%. When your period is over, you can sell some amount of holdings if you want or you can sell some amount of holdings according to your need, but selling all the money is foolish.