> Prediction markets -- or really any price system -- aggregate the best available information about the future.

The best information available to those participating in the market (in good faith).

> Now, say that you somehow knew that this coin wasn't a fair coin

So insider trading?

I appreciate the verbose response, but the original comment implied that prediction markets literally predict the future... Which as you've stated they do not.

I'd contest the idea that they aggregate the best information too. Since they seem highly amenable to manipulation, the metagame of convincing the market that a given future is more or less likely seems more profitable.

Confidently stating a given markets prediction is wrong would involve accurately predicting the future... If one could do that consistently, a prediction market would be unnecessary to accruing wealth and power.