Inside Mark Zuckerberg's Low-Key Billionaire Lifestyle

There's one thing Zuckerberg doesn't seem to mind splurging on: real estate. In May 2011, he bought a 5,000-square-foot home — which he's since tricked out with a "custom-made artificially intelligent assistant" — in Palo Alto for $7 million. The next year, Zuckerberg began buying the properties surrounding his home, spending more than $30 million to acquire four homes, with plans to level them and rebuild.

[Photo via Zillow]