When I was 9, I cried all night because I realized that one day, we might meet aliens and go to other galaxies and whatnot, and I would just be dust in the ground by then. The thought of thousands, millions of years of events and me just having been a blip, felt crushing. And there are many people I miss, and many people who died before I was born I would have loved to get to know; that I "made peace" with that doesn't mean it doesn't make me sad. It is sad, it's sad that people die, even after a long life. It's sad for friendships to end. But that I'm sad doesn't mean I'm not also happy and grateful, and prefer to be content with being a single finite thread in a much bigger tapestry of life, rather than just going on forever, kinda defacing that tapestry.

I mean, that's the binary "immortality" option. I'm not against medicine, or people living longer. But if someone genuinely wants to live forever forever, I really would question how much they thought it through.