> They are just ordinary gambling unless you allow insider trading and manipulation, because that’s the only way the market can acquire and represent novel useful information.

Representing only public information without agenda is useful in itself. Words are cheap, and which words you get to see and which words you don't get to see is according to some non-truth incentive. Prediction markets say "you get to make money if you know what the truth actually is". Media says "you get to make money if you entertain people".

It's unfortunate there's also significant negative side effects to financialized prediction markets. I'm more favorable to non-financial prediction markets like Manifold, which say "you get to have social status if you know what the truth is". Seems as though that's the right balance, although you could see how such non-financial prediction markets can be more easily defeated by dedicated non-truth actors if it became prominent in the public conversation.