Microsoft founder Bill Gates has a reputation for being the nicest and most ethical multi-billionaire in the world. He's given away at least half of his wealth, and donates all the profits he makes each year to charity, having long ago decided that he already had all the money he's ever going to need, and doesn't want to swallow up any more. Even a man as generous as that is entitled to a few little perks though, and so we don't begrudge him his island.
Gates settled on the Belize area for his island, buying a piece of land known as the Grand Bugue, which is the largest of the options which were available to him at the time, and attracted a cost of $15m. That's a very high price-per-acre given that it's only 325 acres in total, but as Gates earns $250 every second of every day, he doesn't really have to worry about that now - or ever. True to form, Gates hasn't turned the island into a resort or vacation destination - it's just a private place to relax for himself and his family.