Please explain to me and try to convince me why we should. I’m serious, I just can’t understand why extending our individual lifespan should be a goal of our age, instead of focusing on making our life much better when it’s more worth living.
So we live 80 year lives, but with only about quarter of that really giving all we're capable of, and a fair share is being dedicated to raising children. Living an extra 20 years isn't a perk - it literally doubles our most productive years. Living an extra 40 years with most forms of dementia fixed? That's almost unimaginably more productive, and unimaginably richer. Both on an individual level (working+learning more = earning more), but as a society.
You mentioned "when it's more worth living". Not sure what context you're coming from, but life is a lot more worth living in its second half, simply because you know more about how to live it, and have the means to do it. The only problem is you're getting old and senile.
Edit: please don't downvote somebody asking questions.
Yes, basically as a fellow commenter argues. Thank you for the link.
But in reality, there's opportunity cost to trying to extend your lifespan, it's all the money and attention and other resources that could have gone to improving other much more certain-rewards problems.
In other words, your thought experiment is a fully general purpose argument for any investment. It's conclusion is that you should _always_ go for the investment no matter what the opportunity costs.
Example (1) - We should expand the data center from 80 servers to 200 servers
= Why? our loads are not high, we should instead focus on improving the product
- Well imagine if we already had 200 servers in the data center, would you scale it down to 80
Example (2) - We should invest in renewable energy
= Why? nuclear power is much more certain and mature
- Well imagine if we already had renewables, would you phase it out in favor of nuclear?
In both cases, you're completely missing the point of your opponent by the "Imagine if we already had" maneuver, we don't, that's why your opponent is against it, it's a risky investment with uncertain rewards and plenty of same-utility alternatives (in the opponent's view).