Almost anyone can Form a Market.
The usefulness can only be determined over a period of time and events.
Accuracy is not the best judge of success.
The Profit is the only useful judge of whether or not the Prices are any good.
If you get Winning Overs only one race in ten and muck up the other 9 times, it may not matter.
If that one Winner pays more Overs than the other 9 muckups, there could still be room for Profit.