The betting site Kalshi emerged as a dominant sports betting platform during the World Cup. But the company avoids billions of dollars in taxes by insisting it is not a sports gambling operator.

States are cracking down on sports betting, and a major court ruling bodes poorly for the prediction-market giant.

The betting site Kalshi emerged as a dominant sports betting platform during the World Cup. But the company avoids billions of dollars in taxes by insisting it is not a sports…