If we consider a more concrete example, you will see that this attack can't happen. We can either elect Trump, or not-Trump as president. Everyone agrees that

If we consider a more concrete example, you will see that this attack can't happen. We can either elect Trump, or not-Trump as president. Everyone agrees that we want the price of beans to be cheaper. So there are 4 possibilities: 1) expensive beans + Trump president 2) expensive beans - Trump 3) cheap beans + Trump 4) cheap beans - Trump An attacker doing what you describe would buy up many shares of (3) and (2). To try and convince us all that if trump wins, beans will be cheap. The attacker will need to keep buying up (3) and (2) to keep them more expensive than the alternatives. So the attacker is betting like $100 for every $50 others are betting. Assuming the attacker has more money than everyone else who is willing to participate in this market put together, then the attacker could cause us to think that Trump will make beans cheap. But, there is still the possibility that beans will be expensive, even though Trump won. If that is the case, then the attacker will lose all their money, and will not be able to afford to do attacks like this again. Attacking a market like this necessarily means paying more for something than it is worth, which necessarily means that on average, you are losing a big chunk of the money that you use for manipulations. And everyone who bets against you, on average they are taking your money. I wrote futarchy onto the blockchain with Amoveo.