You are a spokesperson or decision maker for an entity which is bet on, like a sports team or the government. You publicly indicate that you are going to do one thing (probably the thing that makes most sense), so the market bakes that into their assumptions and offers favourable odds for bets on doing the other thing. Then you place your bet shortly before you do the other thing.

(it's true that low level insiders might have limited influence on the actual outcome, but the current suspicion with prediction markets is that some of the participants do have that influence, or are being intentionally helped by people that can)

This gets into game theory and doesn't follow a predetermined flow like you're suggesting.

It's a bit like playing poker...does the guy who just went all in have pocket Aces or not?