This is personal and depends on your perspectives. Obviously the people who want to live longer don't share the same point of view as you. And it is ok, as long as you are not forced to adopt their point of view and vice-versa.
There's miseries in all stages of life. I've known people that still enjoyed life into their 80s and even 90s. I'm not very afraid of being physical uncomfortable, and I enjoy being here enough to want to fight for more time.
I mean, why? Longer lives are not necessarily any happier. In fact, old age seems pretty physically miserable.