If you're at all sane, you probably responded none of them. Nevertheless, billionaire culture seems to involve dreaming up ideal societies. Some are more grounded like Telosa or Belmont, while others are a real moon shot... make that Mars shot, in the case of Elon Musk. One floats on water. Another exists in an a virual dimension. They may not exist. They may never exist. But at least we can learn about them, chuckle, and dream.
Billionaire: Marc Lore (Jet.com, Walmart, Quidsi)
Looks like Dr. Evil?: Yes.
Location: Possibly Arizona
Area: 200,000 acres
Population: 5 million
Model: Equitism (invented for the city)
Attributes: Renewable energy, food residency, water reduction
Inspired by Henry George's Progress and Poverty (free online).
Billionaire: Bill Gates (Microsoft, BEN, Cascade Investment)
Looks like Dr. Evil?: No.
Location: Arizona
Area: 24,000 acres
Population: 80,000 residential units
Model: "Forward-thinking"
Attributes: High-speed digital networks, data centers, new manufacturing technologies
The city would effectively be a suburb of Phoenix, located 45 minutes from downtown.
Billionaire: Peter Thiel (PayPal, Planatir Technologies, Founders Fund)
Looks like Dr. Evil?: Would if he shaved his head.
Location: International waters
Area: 24,000 acres
Population: 200-person resort
Model: possibly libertarian
Attributes: Lawlessness, independent of any nation, allows citizen of existing governments to exit easily
Prototypes were proposed for San Francisco Bay and French Ploynesia.
Billionaire: Elon Musk (X, SpaceX, Tesla)
Looks like Dr. Evil?: Kinda.
Location: Mars
Area: unspecified
Population: several thousand
Model: self-sustaining
Attributes: Partially underground, serviced by SpaceX starships, formed around a propellant pant and solar array
Mars City would produce its own food, power, and fuel.
Billionaire: Jeff Bezos (Amazon, Blue Origin)
Looks like Dr. Evil?: Yes.
Location: Earth orbit
Area: unspecified
Population: 1 trillion
Model: O'Neill cylinder
Attributes: Centrifugal "gravity," Maui-like climate, plant growth
Based on a model developed by Gerard O'Neill at Princeton University in 1976.
Billionaire: Mark Zuckerberg (Meta)
Looks like Dr. Evil?: No, more like Data from Star Trek.
Location: Virtual reality
Area: infinite
Population: 600 million
Model: virtual
Attributes: Most users are presently younger than 13, Roblox is the most popular world, eventual value of $74.4 billion
Criticized by Keza MacDonald of The Guaradian as less a utopia than a "late-capitalist technocratic nightmare".
Honourable mention goes to YCombinator's New Cities with "optimized governance" including universal basic income, urban efficiency, and tech-first systems, and Kim Stanley's Green Archologies self-contained ecosystem with towers complete with agriculture, vertical forests, and carbon capture -- I'll even add Neom, a carless, streetless, zero-emission civilization with AI governance, flying Blade-Runner taxis and robot servants, a dream of MBS. Less-honourable mention goes to the idea of decentralized blockchain cities, the dream of multiple crypto billionaires, where decentralized autonomous organizations replace governments.