It seems that one day in the future, immortality may no longer be out of reach for humans.
If that technological breakthrough happens while I am still alive, I honestly would not want immortality at all.
I would only feel that my life had become meaningless. Imagine a game. You put real effort into training your skills, you play it well, you feel satisfied with how far you have come, and then one day someone suddenly injects cheat codes into it and forces you to play with hacks on. I think any normal person would feel the save file is ruined and would not want to keep playing.
In a world of immortality, you would no longer love someone with everything you have. You would no longer treat the person you love as something precious and worry that one day they might disappear. You could even “love” everyone, until you fall into endless boredom and loneliness. You would no longer have the drive to chase your dreams, your desires, or your personal value, because time is infinite. Your memories, your experience, your morals, your feelings, even your thoughts would stop meaning anything. Every possibility would eventually be discovered, and in the end you would fall into true nothingness. At that point, death would once again become the only real answer.
Of course, this example is extreme. With the human body as it is, we are probably never going to become immortal in that exact way. But without a doubt, it would make people stop cherishing what they already have. It would make the existence of “being human” fall into eternal meaninglessness.
Only because life is limited do people try with everything they have to live a brilliant life, a life they truly want.
That said, I am not really against the average human lifespan, in a healthy state, being extended by another fifty to a hundred years… It does feel like there are many things I want to do that I cannot finish before I die no matter how hard I try, haha.