That???s not the case in Malibu, though, where many of the best houses are literally built on sand dunes.Soon, the Beechcraft was flying over one of Malibu???s premier neighborhoods, the one-and-a-half-mile-long Carbon Beach, also known as ???Billionaire???s Beach.??? Oracle C.E.O. Larry Ellison, the country???s third-richest man, has been madly snapping up properties there, including nine homes f