Earlier quoted context omitted.
You would need some concept of published identity, otherwise they could just create their predictions against multiple different identities each with e.g. 10 predictions.
So actually this wont be a problem. Basically if they do this then each account that they create will only have very few published predictions. So it will be like a coin which comes up head twice after two tosses. The public will not trust such accounts with low number of correct predictions. To build trust you'd need to have a high count of revealed predictions in any given account. That said people can try to game…
edit: and it's also your revenue.