Not the OP, but I think fear of loss is part of it. But a lot of it is just an entrenched/assumed (and IMO not particularly justified) moral valuation of life above all else.
My own view is that a happy life has value. Death is neutral (for the person who dies - it's affect on others may be either positive or negative). And that (all else being equal), causing someone to live an unhappy life has negative moral value.
That latter bit seems to be something that many people not only disagree with, but don't even give proper consideration. Perhaps due to stigma around devaluing of life, so evolutionary bias towards life, or perhaps because their own life is good enough that they find it hard to empathise with those for whom life is an overall negatige experience.
My own view is that a happy life has value. Death is neutral (for the person who dies - it's affect on others may be either positive or negative). And that (all else being equal), causing someone to live an unhappy life has negative moral value.
That latter bit seems to be something that many people not only disagree with, but don't even give proper consideration. Perhaps due to stigma around devaluing of life, so evolutionary bias towards life, or perhaps because their own life is good enough that they find it hard to empathise with those for whom life is an overall negatige experience.