Comment by arter45

Game fixing is a known crime in many jurisdictions. If you are a football/baseball/soccer player and you bet your team will lose, you have an obvious way to drastically increase your odds (especially if you are a top player) - playing bad. Other people are completely unaware of this deal.

Having fire insurance and burning your car is in most jurisdictions illegal. Yes, you should be paid if your car is burned, but if you do it intentionally, you are obviously increasing the chances of getting paid, unless of course the insurance company finds out you did it. And so on.

I don't see why these situations would be illegal and, say, betting against the survival of a regime when you're actually working against it, would be legal.

Things are even harder if you coordinate multiple people. For example, let's say 100 people bet that there will be a riot in town X by the end of the year. X is normally a quiet town so most people bet against. These 100 people bet this will happen 10 minutes before actually starting a riot themselves. Yes, someone could observe last minute trends and might predict reality, but last minute or huge bets are not necessarily true - someone could bet on random things for a variety of reasons. So it's not even useful as a way to get insights into the reality.