[gzread]

That's always been a just-so story invented to justify insider trading. If weather predictors always bet on a weather prediction market, why would anyone else? They'd be guaranteed to lose money.

[Esophagus4]

1) Not all expert weather predictors agree. They can bet against each other.

2) retail traders lose money and know far less than institutional investors, but do retail traders participate in the stock market? Of course they do.