Subtitle: "Bryan Johnson, the longevity guru, wants to live forever. But the big question is why."

Answer: Duh, that's why. If you're perfectly healthy and doing what you enjoy every day, then on which day exactly do you plan to say "time to die?"

Bad marriage? Well you've got all the time in the world to fix it or quit or find a new one.

Dead-end-job? You've got all the time in the world to be a homeless bum until you upskill and find a better one.

Bored of the same routine? You've got all the time in the world to try a dozen hobbies, musical instruments, sports, meetup groups, etc

There's no reason not to live as long as possible as healthy as possible: it's all upside and no downside.