And to spell it out, you can then go burn your neighbours house down and profit from it. Predictions markets don't just predict, they can cause "unlikely" thing

And to spell it out, you can then go burn your neighbours house down and profit from it. Predictions markets don't just predict, they can cause "unlikely" things to happen because they give a way of profiting from making "unlikely" things happen. This is a problem with plain old stock market insider trading too, and with sports betting when the participants take out bets on themselves.