No one. It is parasitic.

Although prediction markets might help get an honest read on what people that bet think will happen, seeing as they outlawed the non profit predictit around 2021 or so, run by universities while giving the franchise to for profit companies, means these companies maximizing revenue will pollute the predictions resulting from seeing how people vote with their money, (a more honest measure than their words.)

Investors, insider traders, fraudsters, the usual.

The ultra wealthy