Seems likely to have been the result of inside information, sure.

But that’s the point of prediction markets, isn’t it? Their purpose is to get people who have knowledge about a topic to put that knowledge out there to the public, with money put up against that to back their certainty. It’s a way of surfacing that knowledge to the general public. People who don’t have knowledge and are just making gambling bets based on their “feelings” are going to get screwed now and then. They probably shouldn’t be doing that.