Edit: I ask because I personally don't see a reason to stay alive while people I love are dying, I don't see a reason to stay alive in an already fucked up planet, while we empty all the resources, etc. But you guys are so smart, intelligent and clever, why even bother.
If you die, you're probably not healthy to begin with, or you die to very sudden trauma.
Yes my loved ones will die and that will make me sad. I'll grieve and move on. My life is not theirs - their death does not mean an end to what I am doing.
Flip the problem. If you could bestow a friend/family member with a thousand years, even knowing you will die, would you?
One of the ancient greek prophets declared the apocalypse would happen in 9 generations. She was quite wrong. Most doomsday prophets are (well, probably all but the last one).
Do you want to live no longer than average, so lets call it no older than 75?
I'd like to be healthy enough to help them when they are dying.