In my personal experience, what motivates people most to pursue life extension is not a love of life, but a hatred of death. Economic gain and the maintenance of “healthpan” are even weaker arguments.
Many of those I know who have been fighting death for years and with great effort do so primarily out of a deep hatred for the very idea of death… The idea that subjectivity could ever come to an end against the subject’s will. Judging by Yudkowsky’s early posts, which I sometimes revisit, his motivation regarding transhumanism is (or was) very similar.
I’m not afraid of death. In a way, Epicurus was right: when death comes, you’re no longer here, so what is there to fear?
No, it’s not about fear. I hate death; I feel a deep revulsion and rage toward it.
I’m not afraid to die. I feel no fear when I imagine my own death. But I don’t want to let this burp of evolution called aging continue to take my loved ones and animals away from me. At least not until they themselves (speaking of people, of course) want to leave. If they ever want to.
But, of course, at the same time, I would like to live for thousands of years, or even live forever. Not because I’m afraid of dying. Because life is interesting, multifaceted, and full of surprises. And if I can spend that time with those I love—if aging and death are conquered—there is no doubt that I will always choose life.
A love of life may be a reason to fight against aging. But personally, I think that a fear of death is a much stronger motivator.