The over-arching message is that you have less time than you think, be healthy (just because you're skinny and run marathons does not mean you're healthy says my friend the ectomorphic marathon runner who had a heart attack or the other athletic friend that almost died from Deep Vein Thrombosis) and realize that life has already begun.
Average means half died before 66.49 and half died after 66.49. Which half do you think you're in? Which half are you
actually in?
Discussing mortality isn't negative, it's acceptance of the inevitability that those that don't save for retirement are going to get their asses kicked as they outlive their savings, and that those that forgo life in order to hoard money for retirement are just going to end up with some wealthy, entitled inheritors.