Imagine two equally rich people who can't remember how much money they have in their wallets are trying to decide if they should play the following game: Each person takes out his wallet and counts the money inside. Whoever has the least money wins all of the other person's money. Since they are equally rich and have no idea how much money is in their wallets, each has a 50% chance of winning the game. The first person would probably reason that he should play, since he stands to wins more than he could lose; any time you have a 50% chance of winning a bet that pays off more than you could lose, it's a statistically good bet.

The problem is, the same reasoning applies tobothpeople. It would seem that each one has the advantage over the other!