Prediction Markets Going Wrong?

How many ways are there for a prediction market to go wrong?

In my story's current draft, once my protagonist upload has made a few copies of himself, I have him start up a prediction market to try to improve his decision-making, such as the likelihood any given plan will reach a useful goal. (Using currency created ab nihilo via a Bitcoin-like blockchain.) I have his similar copies end up coming to an overconfident consensus, leading to an explosive disaster, leading to attempts to deliberately diversity his copies' mindstates. Initially by simple psychological priming, later by more potentially dubious experimentation.

I only have an interested amateur's understanding of prediction markets, and have nearly no conception of the complications involved, such as what design choices are available when founding one or how many ways one can go wrong (other than the particular item in the previous paragraph). If there's anything you'd like to see in a story with a prediction market, or if you have any advice or references I can read up on, I'd appreciate your input.

(The idea I'm currently pondering: if it would be feasible to use a prediction market to generate answers to the question, "Which rights (or 'rights') should we include in our constitutional Bill of Rights, and which should we leave out?")