Most people who play commodity markets… lose their stake and quit within a year. Such markets are dominated by the minority who have managed to play and not go broke. If you believe otherwise, and know of some market where the prices are obviously wrong, I challenge you to ‘put your money where your mouth is’ and take some of that free money you believe is there for the taking. It’s easy to bad-mouth the stupid public before you have tried to beat them.

Robin Hanson, ‘Could Gambling Save Science? Encouraging an Honest Consensus’, Social Epistemology, vol. 9, no. 1 (1995), p. 22