Chronic pain, immobility, severe mental disabilities (senility) etc. Is it really that hard to imagine a scenario where life isn't fun for someone at an advanced age?

Oh man, so many things at very old age. Difficulty moving, leading to an ever increasing cascading series of health problems. Big debilitating diseases like dementia or alzheimers. Anything that can cause being bed-ridden the new permanent normal.

And lets not forget the final stage, the potential 1-3 months (like my grandma) of life. She had finally had enough of the pain and difficulty, but she had to just let the disease take her over rather than end her life right then. So she spent 6 weeks in agony with a nurse 24/7 solely to manage pain.

Yea.. i don't get the appeal, personally.

Chronic pain is the first thing that comes to mind for me.