I hold that opinion because a variety of Quiz shows are commercially successful. I think most entertainment has experiences with short feedback circles.
I don't see how the event you propose is about updating on evidence. Updating on evidence in the sense it was done in the Good Judgement Project needs longer time frames than a tournament of a few days.
I see that the offline model doesn't let people compete on research abilities but competition on calibration still gives you an event that's about probabilities. It has the advantage that the players can make a lot more predictions in a short time frame and it's less likely that the tournament gets won by lucky overconfident participants.
A 2-day event where people do 1 hour research per question likely doesn't give you a dataset that allows you to pick a winner based on skill.
So, I've been thinking about prediction markets and why they aren't really catching on as much as I think they should.
My suspicion is that (beside Robin Hanson's signaling explanation, and the amount of work it takes to get to the large numbers of predictors where the quality of results becomes interesting) the basic problem of prediction markets is that they look and feel like gambling. Or at best like the stock market, which for the vast majority of people is no less distasteful.
Only a small minority of people are neither disgusted by nor terrified of gambling. Prediction markets right now are restricted to this small minority.
Poker used to have the same problem.
But over the last few decades Poker players have established that Poker is (also) a sport. They kept repeating that winning isn't purely a matter of luck, they acquired the various trappings of tournaments and leagues, they developed a culture of admiration for the most skillful players that pays in prestige rather than only money and makes it customary for everyone involved to show their names and faces. For Poker, this has worked really well. There are much more Poker players, more really smart people are deciding to get into Poker and I assume the art of game probably improved as well.
So we should consider re-framing prediction the same way.
The calibration game already does this to a degree, but sport needs competition, so results need to be comparable, so everyone needs to make predictions on the same events. You'd need something like standard cards of events that players place their predictions on.
Here's a fantasy of what it could look like.