I would happily live 500 years if I could keep the quality of life prior to old age. The issue isn't a number, it's what your life is like in those last 20 years. I can't imagine we will regularly get to 120 without slowing the aging process, which would improve quality of life.
I've enjoyed a fairly privileged life in recent years so I suppose that changes my perspective. I fully recognize that not everyone is dealt a fair hand, whether it be financial or the chemicals in ones brain. Though even when I was poor and less mentally together, I always valued a long life. There are so many interesting things in the world, I want to live long just to see what happens to humans. Will we get over our fundamental flaws as a species, will we make it to being a space faring civilization? Will we protect the environment and create artificial consciousness? Also I value new experiences and life always offers more.
Because a world in which people live to 80 tend to live well till 65, And a world in which people can live to 120 might open up the possibility of living well to 90.
Stretching out life expectancies tends to stretch out the length of quality time too.
Are you suicidal? Longer life does not mean living as a cripple, we can extend our health if we research more. And exercise and lower calorie diet seems to improve health a lot. A 70 year old who exercises and eats lightly will be healthier than a 30yr who eats like an American and drives without walking much.
I'm close to your age and I'm excited for the next 40-50 years. It often surprises me when I get perspectives like yours. I have to remember people have different opinions on things I take for granted.
We can have a tendency to project our views onto everyone else and assume everyone thinks the same thing. False consensus effect
I think people are fundamentally different because of some stuff that happened in childhood. There are people who are negative about the past and positive about the future. I fall into this.
There are others that are positive about the past and negative about the future. Maybe you're here.