Neither the sun nor death can be looked at with a steady eye. La Rochefoucauld, 1613-1680.
Older adults are less likely than the young to believe there are things that can be done to control aging-related declines in areas such as memory.
It seems to me that the threshold of just how infirm you would have to be before you would rather die also rises with age. The young think they would tolerate only modest reductions in health and function, while the old actually tolerate very large reductions.
Rage if you will against the dying of the light, or take a chance with cryonics, but believe it: you will most likely age, become infirm, and die.
(Yes, I know, someday technology may change all this. But not soon.)
Added: On p.120 of the 12/25/06 New Yorker is a cartoon with the caption, "Donald is such a fatalist – he’s convinced he’s going to grow old and die."