Comment by stubish

Insider bets distort the probabilities, creating a conflict of interest and causing market manipulation. We don't let athletes bet on their own games, because some will deliberately lose. They will do this when the odds are good and they will make more money. So you don't get accurate predictions, because the more probable something is, the better the odds and the more money to be made by someone manipulating the odds.

End result is you place bets against things you want to happen. eg. USA invading Iran. If you win the bet, you make money. If you lose the bet, you still win because the USA invaded Iran. And maybe that happened because people in power took your bet and influenced the odds in their favor. A fully deniable market for bribes. Same reason you can't bet on unnatural death, because it crowdsources assassination.