> Personally, I feel that any state that allows sports betting is going to struggle to argue a case to ban prediction markets because you're essentially arguing over implementation details.

This seems to be based on the false assumption that state legislation on distinct but related topics must generally be based on a coherent, consistent rationale. This is, very much, not the case under any law that binds US states, nor is it a rule that, despite not existing in binding law, is in practice imposed as a constraint on state governments by the actions of the voters.

(Conversely, even if such a rule was imposed, in law or otherwise, any state that has rules regulating the offering of insurance contracts, including who could buy insurance against what events—which, as it turns out, every state does—would have exactly the basis they need to apply the same kinds of rules to prediction markets.)