Polymarket and Kalshi are currently hotly competing for prediction market dominance, and are about the same size. This resolves once that is no longer the case, and one is dramatically more successful than the other.

I don't want to define a single metric since that can be goodharted, but I'm looking for roughly a 90/10 split or better of general prediction market mindspace and finance-space. (Between them only. The emergence of a third competitor doesn't factor in.)

For comparison I would say that Kalshi seems on vibes to be pretty close to beating PredictIt, or possibly has already.