Both my parents died, so i'm no stranger to it or suffering in the world. It's that suffering which drives me to want to improve the world so much and be optimistic about what can make things better. Though I do have high hopes for transhumanism and life-extension breakthroughs (some believe those who are under 60 today could potentially live 1,000 years if current trends continue, read some Ray Kurzweil or Aubrey de Grey), I of course will not deny that as far as we know today, everyone will die and people will suffer. Okay. So? Is that the whole story? Don't we have steps we can (and, I'd argue, should) take today to limit suffering and extend joyful life?
I like thinking long term which is why things like the Long Now Foundation are so interesting to me. Yes, we may die, even die as a species, but some future version of us (if we make good decisions today) could explore the universe. Assuming we don't kill ourselves and the planet we have first.
I'm not denying suffering. It's funny because some people have given Marshall Rosenberg (inventor of NVC) that same criticism and yet he developed it within terrible human suffering. Suffering exists, sure. If we claim to be moral beings, I think we should work to minimize it and increase well-being.
"everyone will die and people will suffer. Okay. So? Is that the whole story?" pretty much yeah - You like the long term stuff, there it is.