We always back Jaywalker into a slip, and our stern-mounted 3-by-5-foot American flag was very visible to passersby.

WSJ: Best Places to Retire: How to Retire to the Open Sea

The U.S. also accounts for the bulk of those who are no longer billionaires and have therefore dropped off the list, such as Yahoo's Tim Koogle and Priceline's JayWalker.

FORBES: Billionaires