Eh, I'm a lot less pessimistic about this, some of it is probably socially conditioned and can change with time. I think there's probably a difference between offering a theoretical rejuvenation pill to a healthy 65 year old retiree and offering it to a disabled, cancer-ridden 85 year old woman who is going blind from macular degeneration. I think as the pain of aging compounds with time, the rejuvenation pill looks more and more appealing. And I suspect that much of the "tired of life/ready to die" attitude old people have (to a certain extent this may be something they say because it is expected) is a response to their low energy levels and the background level of pain they experience. I doubt if you actually rejuvenated an elderly person to a youthful state they would persist in welcoming death.