Location: Lanai, Hawaii 
Purchased: $300 million*
Current Value: $346.53 million*

Larry Ellison is worth $101.9 billion, and the Oracle billionaire decided that he wanted to do something ecologically-beneficial with his money. He owns 98% of Lanai, a private island in Hawaii, which is home to just one town: Lanai City. The rest of Lanai is owned by the Hawaiian government and is home to a few private homes.

Ellison’s vision for Lanai is that of an environmentally-friendly dreamland. He bought his share of the island for $300 million in 2012, and he has spent $500 million since then renovating it. The “health utopia” is home to Sensei, Ellison’s wellness company. Sensei oversees solar-powered greenhouses and spas. Ellison called his stake in Lanai a “microcosm” for what he wants the world to be.