As a person who has lost loved ones to cancer and has advocated for others the medical system was ready to write off but who recovered, left hospital, and lived years longer, the nihilism in your comment is alarming. If you work exclusively in hospice or exclusively with terminal patients who want only palliative care, it may be alright. Otherwise, it's very concerning.

Why change a tire on your car, given that the car only has "a few more decades" (likely less) of useful life left? The engine might blow up before that or it might get totaled in an accident.

Why darn a sock when, after a few more wash-and-dry cycles, the material in other places will have thinned enough that it has to be replaced anyway?

Why plant a tree? It may be attacked by insects or blight and die as a sapling. Or it may be cleaved in half by a lightning strike.

Attempting to persuade or funnel a person facing certain or near-certain death but who still wishes to fight for their own life into giving up or refusing or discouraging them in their attempts to eke out a bit more life is reprehensible and unforgivable and something I hope you have never done.