Yeah, I saw that situation with my wife's grandmother. My wife still says (without a trace of irony or guilt) that she stayed alive out of spite, just long enough to finish burning through all her money to make sure there was nothing left as an inheritance. It sounds incredibly bitter, but then you'd have to have known this woman...it's an entirely plausible theory.
We have an awkward societal situation where we have the technology to prolong someone's life by decades, but lack the maturity to recognize that in many cases we probably shouldn't.
At some point when I'm about 78, or perhaps when old and I feel myself going mentally, I fully intend to give a bullet a tour of my brain. This is my personal plan only.
I personally, as long as i'm compos mentis, want to live for a very long time. In my family, we often either suffer dementia at about 70-75 on one side, and others usually maintain completely sound minds until their death aged 90-95.
Out of my great-grandparents who lived/live and died during my lifetime:
One has severe senile dementia, age 89. First manifested in her 60s. Had a history of mental illness, and was in and out of institutions.
One remained entirely compos mentis until his death of a stroke age 92.
One is still alive, still has awareness and can enjoy life, age 92.
One was completely compos mentis until his death of mesothelioma age 80.
One was completely compos mentis until his death of lung cancer age 78.
One is still alive, completely compos mentis except is a little forgetful and sometimes lapses into her mater lingua.
The remaining two died in the 1960s, so I never met them.
I reckon I'm going to live a long time, but I agree with Truean- if I have no awareness, ie. Reudh is gone, then what is the point of living? You would be just a shell that lives in pain for the rest of its life.