Legal experts in South Korea are warning traders that using overseas prediction markets like Polymarket could result in criminal prosecution, after one user banked $160,000 profit from correctly backing an underdog candidate in Seoul’s mayoral election.

The Winning Trade

The trader, known as JackinT on Polymarket, placed contracts on the June 3 Seoul mayoral race when conventional wisdom heavily favored the Democratic Party’s Chong Won-oh. Exit polls had given Chong over 51% support, with the incumbent Oh Se-hoon trailing by more than five percentage points. Then Oh surged during late counting to win by less than one percentage point, delivering JackinT a 106% return on stake. The user also made smaller profits on other mayoral contests and gubernatorial races, rising to position 36 on Polymarket’s monthly leaderboard.

It’s the kind of successful contrarian call that prediction market enthusiasts dream about. The problem, though? According to unnamed legal analysts quoted by the Joongang Ilbo newspaper, South Korean law may classify such activity as gambling. If prosecutors successfully argue that prediction market contracts constitute betting, traders could face fines of up to 10 million won, roughly $6,500.

Where the Legal Grey Area Lies

South Korea’s Criminal Act prohibits residents from placing bets on overseas casinos, both physical and online. But conviction requires prosecutors to prove that prediction market activity actually falls under this definition. That distinction matters considerably. Traditional gambling involves wagering on games of chance. Prediction markets, by contrast, involve contracting on real-world outcomes based on available information and market pricing.

The legal uncertainty reflects a broader challenge regulators face worldwide. Prediction markets operate in jurisdictions where gambling law was written with betting shops and casino tables in mind, not crypto-native platforms trading on political and economic events.

Broader Election Controversy

The Polymarket alert comes amid heightened sensitivity around gambling in South Korean politics. The June 3 elections themselves sparked gambling-related controversies when candidates faced accusations of casino visits. Education superintendent Kim Dae-jung admitted visiting a casino during a work trip to Vietnam but denied actually gambling there; the controversy didn’t derail his election victory.

Gambling concerns have also touched South Korean professional baseball. Four Lotte Giants players recently returned from suspension after being caught placing bets in a Taiwanese gambling establishment.

The Bigger Picture

For traders and the prediction market industry, South Korea’s stance represents a potential complication in markets already operating in regulatory grey zones across Asia. JackinT’s successful trades were entirely transparent and executed on a regulated platform, yet the possibility of prosecution illustrates the real risks players face in emerging markets for event contracts.

What the team thinks

Sheena McAllister says:

Carl raises an important point about jurisdictional enforcement challenges, but I’d argue South Korea’s aggressive stance here reflects a broader regulatory pattern we’re seeing across Asia: governments are struggling to distinguish between legitimate prediction markets, which serve genuine price discovery functions, and illegal gambling operations. The real story isn’t the $160,000 win triggering enforcement, but rather how prediction markets’ borderless nature is forcing regulators to either develop clearer frameworks for legitimate political contracts or continue pursuing users through increasingly difficult extraterritorial prosecution, a path that may prove both costly and ineffective compared to regulated domestic alternatives.