The young care more about the future because they worry how emerging problems may affect them, and death is distant and abstract. Whereas older people feel their mortality more concretely, and wonder how they extract as much in the time they have left.
In your 20s or early 30s financial shocks are generally a lot less scary because you can still pivot, life will just be a little tougher for a while. At 60, it's usually utterly terrifying.
I think the only thing that will happen for sure if we make people live forever is stagnation as all the people who feel strongly about something that is wrong don't die off and instead accumulate, likely filling up good positions in society that otherwise would have gone to a younger, more dynamic up and coming person.