Mortality is the number one problem every single human being and all of our fore-bearers, down to the very first single cell organism, have and have ever had in common. It's the end, te path to nothing. Perhaps you believe there is more. Whatever comes next, death is fucking scary.
I believe it's very natural to do everything in our power to prevent death or at the very least delay it, and to convince others - whose pain we don't feel - to do the same.
I can't even begin to imagine how miserable a person must feel when they are decided that they're leaving us early. It goes against millennia of both collective, and also ones own individual fear and uncertainty. With my liberal Dutch upbringing, have nothing but respect for that.