I get your point but should someone cut out a part of their holdings just because they feel too old or they think that age is not on their side anymore when they already have other source of income to take good care of themselves at that age. For me, age should not even be a reason why we should consider selling our bitcoin so far as we can still sort out our daily needs outside our investment in bitcoin. The only way someone can decide to sell part of their investment in bitcoin when they feel they are getting old is in a situation whereby all his major investments is in bitcoin and he doesn't have any other source of income.
In the area where you talked about we not having control over our lives, it is true but if an investor who has other source of income is not confident about their health condition, what they need do is to start preparing early to expose the security information of his holding to someone who he trust so that if eventually, unforeseen events that can lead him to not being able to reveal the security information to anyone happens, the person they gave the security information can inherit the holdings and start from where he stopped and while revealing security information to people you trust, it should be someone who knows the value of the asset so that they don't end up selling everything when you are no more.
The choice for when they already think that their age is not long anymore or more on the alertness if age is not on their side then the choice they must make is to pass on the password to their children.
Indeed, in such conditions people usually do not think healthily anymore or their memory has decreased so at the age of 60 or 70 it is better for them to pass on the password earlier to their children.
In the long term everything we want can happen but don't be too afraid because we can tell you early. There is no need to sell bitcoin if it is not necessary because getting the same entry as before will be difficult to do, so just maintain it by holding it in the long term so that the benefits can be enjoyed by our children or grandchildren at some point.