People treat happiness as a good unto itself. Why? "People like being happy"? That's circular. "There's no other point to life"? So?
Desire for immortality reads as a cope. You have picked a goal in life that is truly pointless. You recognize that. You therefore want to compensate by trying to get as much of it as you can. Unfortunately, you can't compensate for pointlessness with volume. (Just as you can't compensate for losing money on each sale with volume). If you pursue something worthwhile, then you need precisely however much time it takes to do that thing, then you're done. You won't reach the end and still feel anguish at having no time left.
I see pursuit of immortality as deeply immoral. There are other human beings waiting to be born into the world. We have limited space and resources, capable of supporting a certain maximum number of people at a time. You want to take as much of that time and space for yourself, even at the cost of preventing others from being born. This frequently coming from supposed altruists. Cryonics is similarly deplorable. You, like everyone who came before you, are going to die. But right before you die, you are going to have your body frozen in time, at the moment before your death. Then you are going to demand that the people of the future, who themselves face the inevitability of death, unfreeze you and extend your life, rather than bringing their own children into the world.
Of course, if we look at it from the other perspective, immortality is not only currently achievable but trivial. And, furthermore, it costs your ancestors nothing. The trick is to perceive the universe as being made up of little cells of spacetime. You're goal is to put something into one of those cells. Once you've done so, it will stay there for the rest of all eternity. In fact, you do this every day (every instant), so there is no trouble in putting things in these spacetime cells. Rather, the trouble is deciding what to put in them. Naturally, if they are going to last for the rest of all eternity, you ought to pick something pretty special to go in them.
https://www.scottaaronson.com/papers/philos.pdf (section 10) "In complexity theory, the difference between space and time manifests itself in the straightforward fact that you can reuse the same memory cells over and over, but you can’t reuse the same moments of time." (so make the most of them)
http://thecodelesscode.com/case/234 "TEMPORARY, I HOPE HOPE HOPE/The code beside persisting to the last—/as permanent as aught upon this sphere—"