When Eli Goldfine messaged me on X, I thought it was a joke.
He said he wanted to help me with my prediction markets beat. "Prediction markets, AI, the universe. 13yo," his bio read. I didn't immediately spot the statistics reference in his username, @realTomBayes. When I asked him who he was, he replied: "My name's Eli, I am legit 13 years old."
I knew the prediction-market industry skews young; the founder of Polymarket and cofounders of Kalshi are 27, 29, and 29, respectively. Many users are in their 20s, and 18-year-olds can use them in the US. Last fall, Kalshi was briefly in business with a 15-year-old gaming influencer before its legal team concluded that they "can't work with minors rn."
Eli, who spoke to me on a video call from New York's Westchester County with his dad Evan listening in, looks every bit 13. A few days before, he livestreamed an interview with two ex-Kalshi employees about their new prediction markets investment fund, 5c(c) Capital, with his braces sometimes visible. It was the kind of content that business news outlets would love to publish, but a middle schooler with a Substack and a few dozen followers on X got the scoop.
"I guess now I'm slightly more credible," said Eli, noting that his follower count jumped to over 300 in the wake of the interview.
"Will I get an A on my essay?"
Evan, a commercial real-estate developer, said he and his wife, a psychologist, are just along for the ride.
"It's not pushed by us at all," he said. "We're supportive because he's finding it interesting."
Eli said the first prediction market he learned about was Polymarket. He got hands-on experience by creating an account on Manifold, a play-money predictions platform that has been popular with the so-called rationalist movement for years. Eli said one of his early successes came in May, after he created a market where his classmates could bet on who would win student-government elections.
"My school didn't like it," he said. (Evan confirmed this.) "Everyone was just trying to bet their preferred candidate up to 99%. I made a lot of profit there, obviously, by just betting it back."
Eli shared a link to the market with me. He appeared to have roughly tripled the amount he put at risk.
In the months since, Eli bet on and created a wide range of markets, some serious and some not. He read economists like Tyler Cowen and Robin Hanson, an early advocate of prediction markets. The impact of their libertarian-ish thinking is reflected in a market he created on Manifold: "Will I get an A on my essay about an organ market?"
His views are still evolving. While he's excited about the potential in prediction markets, he doesn't see a point for sports markets — "they don't provide any utility whatsoever" — and thinks traditional sportsbooks and state lotteries are exploitative.
Want to hire a 13-year-old intern?
Besides prediction markets, Eli's passion is making and using telescopes. He joins his dad for trips to northern Westchester County, where more stars are visible at night. Last year, for the astronomy magazine ScopeTrader, he interviewed optical designer Al Nagler, who died in November.
On a bookshelf in his room, a well-used Charlie Brown box set and a collection of Calvin & Hobbes books stand next to books on optics and algebra.
Eli told me he does most of his homework on the long drive to school in the mornings. He regularly posts to his Substack, "Bayesian Supercycle," which he launched in January. This week he spoke to staffers at Microsoft Research about one of his projects, a website with tools for testing automated market makers, which provide liquidity on some predictions platforms.
Coming up, he says, he has interviews set with several top forecasters on Metaculus, a long-running predictions site whose users skew towards science and technology enthusiasts.
He said he recently enabled subscriptions at the suggestion of his dad, who has been writing his own Substack, "A Year of Bach," since 2024. Eli said his goal was to get his Substack promoted to other users, not to make money.
Eli ended his interview with the 5c(c) Capital co-founders, Adhi Rajaprabhakaran and Noah Zingler-Sternig, by asking for a summer internship.
"I think we might have to talk to your parents and make sure we're not violating any child labor laws," Rajaprabhakaran said.
Eli said that opportunity didn't work out, but another prediction-markets company already offered him a summer gig. And another firm, Thrive Capital, tried to connect with him through Rajaprabhakaran, Eli said.
He said he hasn't given much thought to high school, college, or a career. For now, he's weighing an invitation to a prediction markets event in Switzerland.
"I'd love to do it, but it depends what my parents say," he wrote to me on Wednesday. "Right now I'm on the bus home from school strategizing about how I will ask them."
