This is a topic in itself. The same goes for losing parents, those who have enjoyed a full, close knit, best friendship type of a bond with their parent(s) and were a phone call away from a chat about almost anything, a problem shared, advice, words of wisdom and physical support be it with childcare or household things have a horrible time when they pass. They've loved and lost, at they say. The price of love, if grief.
Whereas those who almost grieved for their parents whilst they were still alive due to not having that bond, really escape the grief altogether.
In conclusion, anything we have, we risk losing - looks, brains, wealth, love, family members, health.
Another example. The more active a person, is it harder when they lose their mobility layer? Look at professional footballers who retire young, many fall into depression, whilst the rest of us kick start our careers at the same time. Mind you, we never had what they had in our early adulthood - praise, success, fame, millionaire wealth, opposite sex throwing themselves at you.