I believe the correct way to do this, at least in theory, is to simply have bets denominated in the risk-free rate—and if anyone wants more risk, they can use leverage to simultaneously invest in equities and prediction markets.
Right now I don’t know if it’s possible to use margin loans to invest in prediction markets.
You could technically say Google is a marketing company, but Google’s ability to sell search ads doesn’t depend on being good at marketing in the traditional sense. It’s not like Google is writing ads themselves and selling the ad copy to companies.