[Kate!]

Saw a great post from Jords earlier, totally agreed with it. Saying that the housemates were clearly told that whoever went for the lowest amount WOULD leave with it.

Obviously then choosing the maximum amount guaranteed that Sam could not possibly be the one to get any money. If he was greedy then he'd snatch the chance to try and steal some prize money and run with it, rather than stay and take the chance of no financial gain whatsoever.

It's as straightforward as that.

Dexter wanted to take the money, he calculated the risk and it did pay off insofar as he managed to pick the lowest amount of walking money. How his face must have fallen when the truth was revealed he wouldn't get to walk with the money. Now that's greed.