At Manifest, the Berkeley festival where the prediction market movement gathers, founders confront a product whose trading volume is now dominated by sports contracts and rising concerns about gambling.
Manifest, the annual retreat for the rationalist community that incubated the modern prediction-market movement, met this June at Lighthaven, a Berkeley compound at the center of that movement. The session list read like a workshop on epistemic improvement: calibration games, forecasting tournaments, talks on epistemics and AI risk. Offstage, though, the platforms those founders helped build were starting to look like a different product.
According to Pew Research, sports contracts now account for roughly 80 percent of Kalshi's trading volume and 39 percent of Polymarket's, a split Wired flagged in a May 2026 analysis. Inside the Manifest compound, the gap between the festival's truth-seeking mission and the platforms' actual user base showed up in a smaller detail: many attendees were unaware that Kalshi had run a June 11 ad campaign starring Timothée Chalamet, a celebrity-driven marketing push aimed at the sports-betting crowd.
Dan Schwarz, who cofounded FutureSearch and previously led Google's internal prediction market, told Wired that sports contracts were "degenerate gambling" and that prediction markets "would have to deliver a lot more value than they are now" to outweigh the harms. Schwarz floated an alternative path the rest of the movement has not endorsed: the United States could ban sports gambling outright while leaving other prediction markets legal.
David Bensoussan, a Manifest session organizer who has made about $1.6 million trading on the platforms, put a sharper version of the same question to Wired: "Truth-seeking mechanism … what on Earth does that have to do with sports?"
The founders are not alone in raising the alarm. A peer-reviewed analysis published in Science in April 2026 described prediction markets as having a "gambling-like design" and warned of "public health concerns" and the risk of "democratic manipulation." Ipsos polling has tracked Americans gradually moving toward seeing prediction markets as closer to gambling than to forecasting tools. State attorneys general have filed consumer-protection lawsuits, and insider-trading scandals, including a documented Polymarket case involving bets on the capture of Nicolás Maduro, have surfaced as warnings about manipulation risk.
The industry is responding with a Washington playbook familiar to anyone who watched crypto mature. The Coalition for Prediction Markets, a new trade group, is advised by a former Democratic lawmaker and counts Crypto.com leadership on its board, according to Wired. Kalshi, for its part, continues to insist on the distinction its spokesperson Jacki McGavick made on the record: Kalshi runs an exchange-style model in which customers trade against each other, not a house-banked casino. Both Kalshi and Polymarket declined to comment on why neither sponsored Manifest this year after backing the festival in prior years.
The rationalist founders did not lose the argument. They won it, and the product that emerged looks nothing like the one they had in mind. Schwarz's framing, one founder's view rather than a movement consensus, captures where the fight is now headed: regulators carving sports contracts out of the legal prediction-market category, or sports contracts defining the category outright.