Not sure if you are making a nuanced claim about the proportions of self-identified adherents who actually subscribe to orthodoxies, but the population statistics generally cut against your claim.

https://www.statista.com/statistics/374704/share-of-global-p...

If not "the majority", then a proportion conceivably large enough to affect the polymarket results.

Isn't that subset of the population also very likely to believe that gambling is haram?

Technically, prediction markets aren't gambling, they're soothsaying, which is a form of witchcraft punishable by death.

Don't you need to be using magic for it to be soothsaying?

Isn't the entire field of Islamic finance legal (moral?) loopholes that turn the haram into halal?

No.

Touche