Hyperloop and Elon Musk's massive boring drill could have been a cover story for building underground bunkers/cities. It's still a question mark on my radar.

The Hyperloop would make a good bunker for plebs waiting out a disaster...

If you think about it that way, then shouldn't there be a campaign to build underground bunkers to save humanity from all kinds of doomsday scenarios? Start on it now. But that would scare some people, and those scared people might actually trigger doomsday themselves. So they wouldn't tell us if emergency bunkers were being built for all the plebs.