alt Hacker NewsDisclaimer: I have not read any literature on the economics of prediction markets, and I know nothing about the mechanics of Polymarket/Kalshi.
I would imagine that in theory, everyone thinks they have the best information at the time, something like:
House: "Odds that X happens? We'll put $1 on both sides to get it started. 50/50."
Someone comes along: "Oh dang, I'm definitely more than 50% confident that X is happening. Let me put $1 in." Now it's 67:33.
Someone else comes along: "Oh I'm more than 67% confident X is happening, let me put $1 in." Now it's 75:25.
And of course, you get people going: "I'm more than 25% confident that X is _not_ happening, let me put $1 in!" And now it's 60:40.
The murky part, I would imagine, comes when the odds and the payout actually act as something that influences the outcome, but in perfect theory-land, if everything goes as planned, this should move the odds to the most informationally-accurate measurement, which should, in theory, benefit observers by making this measurement public.
Sure but these things are not really "odds" anymore, right? The most searched terms might be a mystery to the general public, but not to the engineers at Google. It gets even murkier when you can influence the outcome. The exact temperature at an airport might be difficult to predict, but if you are able to hold up a hair drier to the sensor for a few minutes you can be pretty sure it won't be cold.
When the other side either has information that makes it not a bet, or if they have means to influence the odds, the best outcome for outsiders is to not play at all.
And of course, the entire conceit relies on the idea that more accurate information to the public is always good and always outweighs the negative externalities. But is it really all that important to the public good what the most searched artist is on Google in a certain year? Or if an announcer will say a certain word during the super bowl?