What do they expect to be doing at 1000 years old?
The explanation that springs to mind is that young techies lured by longevity expect to be part of "the only generation". Anyone older is too out of touch, and younger generations basically won't happen as immortals can't have kids nilly-willy. So the world would be eternally ruled by a cabal of geriatric techies born around 1990. Now that's a dystopic thought!