I can't believe how many people take the 1 million. I can understand some of the reasoning, but mathematically it's a stupid decision.
Yep. 1 million < 50 million (which is the value of the 50% chance of 100 million)
But if you think of the actual value of each of the prizes - not the monetary value, but the amount of personal value each individual gets from that amount of money - it makes more sense, even mathematically. For most people, going from zero to 1 million makes a bigger impact than going from 1 million to 100 million does. Diminishing returns, etc. I'd imagine if people had financial security and a good amount of money already, they'd be more likely to gamble for the 100 million - an extra 1 million has less value to a millionaire than it does to someone struggling to make ends meet. Mathematically, it's like a percieved value of, say, an 8 (a good amount of money, some financial security) vs. a 50% chance of something with percieved value of a 10 (being filthy rich).
Also, risk aversion and all that. Guaranteed 90 million or 90% chance of 100 million? Mathematically a neutral decision, but most people would pick the safe bet to avoid the risk. (Plus, that extra 10 million once you already have 90 million doesn't have as much percieved value as, say, the first 10 million, to most people).
Anyway, chose a guaranteed 1 million. As Implode says, if you've only got one chance at it, the 50% chance of going away with nothing makes a guaranteed 1 million too much to pass up on for someone like me who has yet to graduate, has no assets etc.