Because you can easily collude and cheat at poker so it needs to be heavily regulated or outright illegal to prevent theft. You can't really cheat at prediction markets, unless you have insider information which they can litigate after the fact.
Surely you’re being facetious, insider trading is obviously a huge problem that is rarely enforced and we’ve already seen instances of people actively influencing events or using false information to fake the result of a bet
The one I remember is from Polymatket, about whether Trump would end the Gaza war by a certain date. I bet no, and it resolved to yes on the basis that Trump said that he ended the war.
