Bonus: Larry Ellison's Hawaiian island home on Lanai

Estimated home value: $300 million

Title: Co-founder and CEO, Oracle

When it comes to Oracle CEO, he just goes a little beyond this list, as he not only owns a posh house on Lanai, Hawaiian island; he also won about 90 percent of island itself. The Maui News originally listed the price at somewhere between $500 and $600 million, but Ellison paid $300 million for it, the Wall Street Journal reported last month—quite a steal for the 141-square-mile island. As for the other 2 percent, it's either owned by the Hawaiian government or long-time Lanai residents.

Ellison revealed his plans for the island, which include an ultraluxury beach hotel that will face the islands of Molokai and Maui, and an endowment of a sustainability laboratory to help make the island 100 percent green and sustainable.

Read Also: 3 Indian Cos In World's Most Valuable IT Firms and 10 Technologies That Failed To Retain Their Dominance