Traditional sports betting allows insiders to exploit static odds. In a liquid prediction market, a large bet based on inside information immediately moves the odds, reflecting that knowledge in the price and eliminating the arbitrage opportunity for the insider.

The case of a trader profiting from advance knowledge of an event highlights a core dilemma in prediction markets. While insider trading undermines fairness for most participants, it also improves the market's primary function—to accurately forecast the future—by pricing in privileged information.

The long-held belief that visible, liquid prediction markets would improve collective wisdom and decision-making has been falsified. In practice, platforms like Polymarket and Kalshi are dominated by trading and gambling behavior, not the rigorous epistemic practice of forecasting.

While prediction markets offer pure, insightful data that can outperform traditional polling, they have a dark side. High stakes can incentivize bettors to shift from predicting events to actively influencing them, including threatening journalists to alter their reporting and swing a market in their favor.

While often promoted as tools for information discovery, the primary business opportunity for prediction markets is cannibalizing the massive sports betting industry. The high-volume, high-engagement nature of sports gambling is the engine to acquire customers and professional market makers, with other "informational" markets being a secondary concern.

While framed as a "wisdom of the crowds" tool, prediction markets can be easily manipulated. Wealthy individuals or campaigns can place large bets to create a perception of momentum or inevitability, effectively using the market as a propaganda vehicle to influence public opinion rather than simply reflect it.

Platforms like Polymarket effectively financialize all information. This creates opportunities for arbitrage based on publicly available, but not widely known, data. For example, a person won a large bet on the length of the Super Bowl national anthem by simply timing the rehearsals outside the stadium in the days prior.

While praised for aggregating the 'wisdom of crowds,' prediction markets create massive, unregulated opportunities for insider trading. Foreign entities are also using these platforms to place large bets, potentially to manipulate public perception and influence political outcomes.

Kai Ryssdal dismisses the reliability of prediction markets like Calci, calling them "black boxes" due to unknown bettors and potential manipulation. He cites a personal example where a dark horse candidate for Fed Chair saw his odds inexplicably spike on Calci without any supporting news, only to lose the appointment.