Comment by TeMPOraL

Plenty of more fun dynamics. For example, in some cases it becomes a way for voting for decisions one otherwise wouldn't control. If a person in position to make a decision doesn't really care about any choice in particular, seeing the prediction market lean one way would incentivize them to choose the opposite, making a short sale immediately before.

It also makes sense for the people voting: by betting against the outcome they want, they end up either a) paying for getting things their way, or b) getting consolation payoff if the decision makers pick the undesired choice.