>Kalshi and Polymarket are mainly just sportsbooks.
How? They sell contracts between two users. One side each. Completely different from a sportsbook where users are betting that the lines they set are not correct.
If they sell contracts on market prediction, then any person doing for example insider trading on corporations, fixing outcomes of sport events, directly paying out others to force event outcome, blackmailing people, or just directly adjusting some result like the CDG weather guy are completely in line with the platform rules and all that is perfectly legal. But since Poly and Kalshi themselves admit that those things are "unfair" and forbidden they have themselves removed their "just a contract" status and transitioned to a gambling status, where indeed fixing matches is bad.
90% of the betting volume on Kalshi is betting on sports. I know how prediction markets work and how they're different that traditional sportsbooks, but they ultimately allow customers to do the same things.
If you are saying Kalshi isn't a sportsbook because the house isn't on the other side of the bet, you might as well argue that DraftKings isn't a sportsbook because they don't actually track your wagers in a book.