What makes prediction markets accurate is when people with inside information put their money in it. But US elections are public enough where there isn't very much that is strictly inside. There are exceptions. For example anyone who would bet now that Hillary Clinton will win the presidency is a fool (for more than one reason 
) because you could be betting against staffers and advisors who know she has no intention of even running and can safely put everything they own in the market. She could even have her own money in it.
The best idea I've heard about this is using a prediction market to predict acts of terrorism. Those bastards will not be able to pass up an opportunity to make some money on it, especially if they can use crypto.
People with inside information only have a limited amount of money to "invest" in the prediction markets. As a result they will not be able to change the market to reflect the exact results and the market has zero way of knowing when someone with inside information is trading) because you could be betting against staffers and advisors who know she has no intention of even running and can safely put everything they own in the market. She could even have her own money in it. The best idea I've heard about this is using a prediction market to predict acts of terrorism. Those bastards will not be able to pass up an opportunity to make some money on it, especially if they can use crypto.
Not the exact results, but enough to make it not worth your while. Let's say you go to the racetrack. Even one guy who knows the race is fixed with $1000 on the board is going to distort the odds enough to take a considerable bite out of your margin. Betting as a business does not have very much margin.
Here's another example, let's say you're playing poker. If the guy next to you can see your cards, you are going to lose, big. But let's say he can see the cards of the guy on the other side of him. Would you still play? Not me, no way, just that little bit of extra information he has is enough to erase the edge of even a skilled poker player at the table who doesn't have the information.
