Mark Zuckerberg is said to have started work on Koolau Ranch, his sprawling 1,400-acre compound on the Hawaiian island of Kauai, as far back as 2014.
It is set to include a shelter, complete with its own energy and food supplies, though the carpenters and electricians working on the site were banned from talking about it by non-disclosure agreements, according to a report by Wired magazine. A six-foot wall blocked the project from view of a nearby road.
Asked last year if he was creating a doomsday bunker, the Facebook founder gave a flat no. The underground space spanning some 5,000 square feet is, he explained, is just like a little shelter, it's like a basement.
That hasn't stopped the speculation - likewise about his decision to buy 11 properties in the Crescent Park neighbourhood of Palo Alto in California, apparently adding a 7,000 square feet underground space beneath.
Though his building permits refer to basements, according to the New York Times, some of his neighbours call it a bunker. Or a billionaire's bat cave.
Then there is the speculation around other Silicon Valley billionaires, some of whom appear to be busy buying up chunks of land with underground spaces, ripe for conversion into multi-million pound luxury bunkers.
Reid Hoffman, the co-founder of LinkedIn, has talked about apocalypse insurance. This is something about half of the super-wealthy have, he has previously claimed, with New Zealand a popular destination for homes.
So, could they really be preparing for war, the effects of climate change, or some other catastrophic event the rest of us have yet to know about?
AI developments only exacerbate these concerns, with industry leaders like Ilya Sutskever from OpenAI expressing fears about the implications of artificial general intelligence (AGI).
Discussions about the potential risks of AGI highlight the anxiety surrounding the rapid pace of technological advancement and what it means for humanity. While some view AI as a path to a brighter future, others worry about the existential risks it may pose, including job displacement and unforeseen societal consequences.
As billionaires prepare for unfathomable scenarios, the societal implications are profound, forcing us to question: should we all be worried?
