Prediction markets can only pay out based on public information, which means that prediction markets can only "reveal information" like this for things that would have been public knowledge anyway. And insiders are always risking that leaking their insider info might influence the outcome of the bet against them (like if leaking the date of a covert military operation causes the operation to be rescheduled), so they're financially incentivized to wait as long as possible before tacitly revealing that information. So prediction markets are the worst possible way of revealing hidden information: you will only learn about things you would have already known, and only when it's too late to make any use of that knowledge.

You're overlooking that sudden, unexplained or counterintuitive movements in the actual prediction market itself, well before the event occurs/market resolves can themselves convey information, about what apparent insiders think (or whales want to manipulate the market to think).

Obvious example: Polymarket now has 69(!) markets involving Iran: https://polymarket.com/predictions/iran

Consider the timing of those markets wrt 2026 national elections in US, Israel, also Sweden, legislative elections in France, Germany (as canaries for their next general elections) plus a possible change in UK PM, plus any possible Ukraine or Venezuela outcomes. And of course events in the stock market or energy markets make certain outcomes more/less likely.

Also, on Polymarket traders often buy and sell before a market resolves, to exploit patterns in other traders.

And consider what happens at major media e.g. CNN now they've partnered with Kalshi, wrt whether the broadcasting certain predictions/viewpoints/interviewees get boosted/suppressed.

There's also a financial incentive to get your bets in early, while the odds are still in your favor. The longer you wait, the higher the risk that your secret becomes public knowledge.

I agree it's not perfect, but I think you're underplaying a lot of the value.