I think it's that everyone can see the odds of something happened that are indicated by the bettors in the market, and that's valuable information that can be c

I think it's that everyone can see the odds of something happened that are indicated by the bettors in the market, and that's valuable information that can be considered the absolute best prediction that can be made based on available evidence. I was watching the betting markets on the night of the 2016 presidential election. As I seem to recall, at the start of the night when people were still basically confident Hillary would win, I was watching electionbettingodds.com and it showed a ~30% chance of a Trump win, so I wasn't so sure. And of course it moved smoothly to nearly 100% as more information emerged and was incorporated into the markets. A good example of how betting markets are obviously not omniscient (or else they would have had 100% for trump), but a lot better than listening to your friends or even the top pundits.