Pundits already make predictions all the time, but no one scores them. Even ones that where the outcome is very clear, like finding a nuclear program in Iraq or Apple making a TV.

So I think it is important to identify what the problem is and make sure you are actually addressing it. Setting up special venues has some advantages, like making sure that the questions are precise and judgeable, and attracting the right kind of people. Prestige for pundits is basically venue. Moving up and down inside a venue is a pretty small scale of change. I suppose that it is possible that if your venue has lots of churn, then the stakes would be higher.

One venue for realish money celebrity predictions is Long Bets, but while the emphasis is on accountability, it sure isn't on building a track record.

Also: does any government other than USA object to prediction markets? I suppose that ipredict's bankroll limitations indicate an objection by NZ, but I'm skeptical that this is a significant limiting factor.