If you have (grand)children, an important reason to wanting to stay alive is often not the fear of dying, but wanting to be there for them and fearing the grief they will endure if you are gone.
And I don’t want that for my kids, or even from the rest of society.
I probably won’t ever meet my grandchildren if there are any, because I am over fifty and single; I probably will never be a parent. So I will have to go a lot sooner if I am not to be a burden on society. But if you think you are going to be a grandparent, you can work on being an irreplaceable and useful one.
Very few people are independent after age 80, and a miniscule amount after 90.