For the other side, let's say I make $X but only need $X/2 to live. Try finding an employer who will let you work half time for $X/2. It's pretty tough, especially if you make $X at something "professional", rather than, say, digging ditches.
Rather than working ~20 hours a week, work ~40 hours a week, half your life.
...except nobody can tell me accurately when half of my life is over so I can retire at the right time.
Note particularly that statistics only work when applied to large enough populations. I will not be 70% dead at 70, I'll either be 100% dead or 0% dead.
...except nobody can tell me accurately when half of my life is over so I can retire at the right time.
So work 40 hours/week for until you pile up enough money to buy a lifetime annuity, and let the insurance company do the averaging over large populations.
That's certainly more viable, but requires much more discipline (to avoid spending the extra money too early) and is probably less beneficial as well, due to diminishing returns and such.
Rather than working ~20 hours a week, work ~40 hours a week, half your life.