“polymarket's 0.047 brier score hides sports markets that are worse than a coin flip”
Critique of the narrative that prediction markets are truth machines. Polymarket's headline Brier score of 0.047 masks category-specific failures like sports markets scoring 0.325 (worse than a coin flip), and 99% of volume concentrates in the final hours before resolution. The author argues prediction markets only work on roughly 2% of listed contracts (binary, high-profile, short-term events with millions at stake), and that when outlets like CNN and WSJ broadcast illiquid market odds as authoritative signal, whale trades on thin books get laundered through credible newsrooms.
Some technical background helpful
Platforms mentioned: Polymarket