Personally, I really like living, mainly because there's a lot of awesome stuff to do and see and build, stories to tell, people to be with, etc. The logical next step is that I don't want to die, at least any time soon or involuntarily. Avoiding death may be difficult, but it seems rather sad to just give up; and anyway, say what you will about humans, but we are pretty goddamn clever occasionally.

So it seems quite worth it to fight death. I don't know if avoiding involuntary death should seem so implausible---humans are machines that can be fixed when they start breaking; that's how ordinary medicine works! I think it would actually be surprising if we could extend lifespans from 30 years all the way up to 100+ years, but couldn't possibly go much further, even given massive future advances in our understanding of biology, neurology, and technology.