One key to happiness according to several studies is to devote a bit of your time to others. Advanced senility deprives you of this once you're unable to actually help another, and I understand how one could want to end it, even without hubris.
Not only will an old person never grow out of his state, he has to carry the burden of being aware of it. This is another huge difference.
Not only will an old person never grow out of his state, he has to carry the burden of being aware of it. This is another huge difference.