I have this fantasy of how, in the end, in the hour of need, all of these bunker-owning elites will be unable to get themselves to their places of safety. Instead, to their horror, they will be consumed by the very 'tsunami', 'meteor', 'fire', etc., that they themselves have created to destroy the population on the surface.

They, too will perish, and their huge, miles-long interconnected bunkers will be empty except for the low-level workers who've been living underground and who've been maintaining the place. So, the janitors, the tech nerds, the food handlers, etc., end up being the only ones alive and will live off the food and wealth in the bunkers, seeding the next generation of humans, who will be low IQ and have no memory or understanding of exactly what happened to tell their future offspring.

The meek (and dumb) shall inherit the earth.