Wouldn't these markets be the perfect "crime crowdsourcing" platform? Let's say a bad actor wants XYZ to happen so they organise a bet on XYZ not happening. Then make sure as many different accounts that they control directly or indirectly bet a lot of money in the same way. Now anyone willing to win the prize can decide to make sure it does happen and get the money (at least a high multiplicator of what they bet themselves).

Am I missing something? Maybe it's already being used in that way... in that case, it would be quite scary.