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In the 2024 US presidential election, prediction markets achieved a double victory: they accurately predicted the result—prompting unmatchable publicity—and they found in Donald Trump a powerful ally and promoter. Donald Trump Jr. is an adviser to and investor in both Kalshi and Polymarket, the two leading companies in the industry. In the past two years, they have exploited a newly friendly regulatory environment to make their profits and popularity soar. Between May and July, the amount being traded on Polymarket and Kalshi doubled , to fifty-three billion dollars a month. They are now worth an estimated sixty billion dollars combined.

Prediction markets let users put down wagers—which look and sound a lot like bets, but with even looser regulations—on almost everything: traditional sports, tomorrow’s weather, how many times President Trump will post on Truth Social this week, even whether Jesus Christ will return to Earth before 2027.…