Polymarket, a cryptocurrency trading platform, is under scrutiny for its claim as a 'truth machine' in predicting real-world events. Despite a strong Brier score of 0.047, indicating high accuracy in some areas, significant discrepancies exist across different market categories. While Polymarket excels in economic predictions, its performance in sports and cultural predictions is notably poor, with scores worse than random guessing. The platform's influence extends beyond traders, as major media outlets like The Wall Street Journal and CNN have integrated prediction market data into their reporting. This widespread dissemination raises concerns about the potential for market odds to influence the events they predict, a phenomenon known as endogeneity. Recent cases, including the use of classified information for betting, highlight the risks of treating prediction market data as definitive truth, especially when dominated by a few well-capitalized traders.