This is the entire idea behind the concept of "assassination markets" - "prediction" markets on assassinations that are just thinly veiled ways to crowdsource murders by taking bets that you expect to lose against an "insider" (the killer).
Futures contracts were a mistake, god damn
It doesn’t need to be as high stakes as assassination. Any public figure could have a free-money loophole with all the stupid bets on things like whether a certain word would appear in a speech.
If I were famous I could start a pool betting on whether I would post a picture of a my lunch this week. I could stake whichever side has the biggest payout and then just make it happen