Ergodicity
Origin: Ole Peters, popularized in investing
Biological Parallel
A population of Thomson's gazelles can sustain 10% annual predation and remain stable—the ensemble average survives through predator-prey-dynamics equilibrium. But individual gazelles cannot be 10% eaten repeatedly—one fatal encounter ends their timeline. Wildebeest herds and African buffalo demonstrate bet-hedging: demographic-stochasticity means individual fates diverge wildly even when population averages hold. Even zebra finches in stable aviaries show individual variance exceeding group means. This is non-ergodicity: what is sustainable for the group is catastrophic for individuals. Peters' ergodicity economics highlights this: strategies optimal for ensemble averages (portfolio across many firms) can be ruinous for individual time-path survival. Effective-population-size matters less than your personal survival probability.