pros:

- its fun for some people

- we can maybe get some limited information about the likelihood of events through a combination of wisdom of crowds and insider trading

cons:

- gambling addiction ruins lives, beyond a shadow of a doubt. People (often people with financial interest) like to argue this point, but I don't have space to write

- insiders essentially steal money from people betting based on other information. You might argue that those other people should have known. But why bet at all? its irrational. Yet people do it regardless, and they still don't deserve to have their things stolen. Poker where another player can see your cards is a stupid game.

- it clearly, unambiguously signals corruption to all and sundry. Connections let you get rich at the expense of others. Some people might not care as much but I truly think this is the biggest con of them all. Why behave the way we would all wish leaders would, if you have proof other leaders are making it big with no consequences. How would you not feel like a fool, for your morals? We should be making it as easy as possible to do the right thing that benefits all.

- it incentivises terrible behavior. Betting that a war won't happen, or a person won't die, or that there won't be an explosion at a crowded area in downtown x city at y time, is essentially the same as putting a bounty out for somebody to do it. They can bet that it will happen, and then go and make it so, and collect your reward money.