Sorry, we ran out of habitat.

How cruel would that be;
Humans finally figure out which genes reverse aging, verify that it works, stop aging related diseases, exploit and distribute the therapies for it, and then;
Whoops, the 1 planet we need to live on (while we already needed 2 more to feed everyone) dies under our feet while we weren’t looking! With an ice-free Arctic, huge methane releases, temperature rise, sea-level rise, dying oceans, crumbling ecosystems, and finally 430 failing nuclear power facilities, we go extinct. We can leave a note on some satellite, saying:

“Sorry, would have loved to meet you one day, and we know it’s hard to understand, but even though we knew how to last forever ourselves, we couldn’t sustain our one and only habitat.”