Fugu
The ultrawealthy love taking risks. It's a personality trait that's likely responsible for most of their money. So it's no surprise that they find one of the most dangerous foods in the world something of the height of luxury. Fugu, a Japanese pufferfish, contains a poison called tetrodotoxin, which is over a thousand times deadlier than cyanide (now that's chic). Chefs are required to undergo extensive training before serving it, and need to obtain a license to buy, cook, and sell it. Because of this, it's extremely rare to find fugu outside of Japan, and even there the dish could cost a few hundred bucks (and you still can't be sure it won't kill you).
[Photo via @seikokirameki]