When "the best way to predict the future is to invent it" is combined with crime it seems clear that betting on crime is acting as an accessory. A business facilitating betting on crime is a criminal enterprise, in the sense of RICO.

Polymarket bets on war overshadow a more basic concern:

War prosecuted by a unitary executive without the express consent of the governed is a criminal enterprise.

Trading in such an enterprise is corrupt regardless of its mechanism.

In a global society, the governed are a world-wide body politic, making war fundamentally a racket.