[tech_ken]

> I'm trying to understand what the criticism is here, because the example seems to support the point that these are meant to be a way of learning the future, not oppose it. I thought the whole point was that yes, people with inside knowledge will bet large sums of money on things they expect to happen, and that's what makes the prediction useful. The market is meant to incentivize people who know things to act on them in a way that makes them known.

You're ignoring the critical issue of timing. It's one thing to crowd-source knowledge in a steady, homogenous way. It's quite another for an actor with material knowledge of the situation to exploit this dramatic information asymmetry to turn a profit, revealing the new information at the last possible timepoint it could be used to lay a wager. Insider trading is quite different from a Hayek-style price signalling, and it's the same here. In principle (and on long time-scales) these markets can incentivize important information to come to light sure, but in infinite time we're all dead anyways. The short-time dynamics matter a lot more, from a social welfare perspective.