It's the billionaire conceit of buying land and (allegedly) installing bunkers in New Zealand to survive whatever they think is coming, but taken to even more deluded extremes.
The key fact is that bunker in New Zealand is likely survivable thing in long term. Not nice(having to actual work and not having modern products available), but survivable. We aren't anywhere close that with Mars.
There seems to be some immense blindness just how hard and fragile living on Mars would be. For decades at the minimum but probably for centuries more likely.
Maybe there's a method to Musk's madness... ...if the world (well, tbh, it'll be mostly the Northern Hemisphere, but it's still going to screw everyone in some manner) ends in ashes, those bunkers aren't going to be as effective at sheltering from regular people as Thiel et al think.
If you're hiding out on Mars, the peons would at least have to build a rocket to get to you when they decided to eat the rich.
There seems to be some immense blindness just how hard and fragile living on Mars would be. For decades at the minimum but probably for centuries more likely.