Unlike stock markets, prediction markets also provide valuable data on important world events, such as elections. It's wisdom of the crowd with financial incentive.
So can a skilled coach make consistent returns in his sport. But sportsbetting is considered gambling.
Surely, in the prediction market, it is possible to set up prediction bets which are practically impossible to predict. And with binary outcome, your odds will be 50/50.
With stock markets, at least in theory that money can be used to make a product to sell. They're not sum-zero games. Even if the company were to liquidate, you would be entitled to a share of actual assets after creditors were paid. This might seem foreign to some modern social media investors who YOLO with leverage all their money on meme stocks, but I would not be against that being reined in too.
Also, I really struggle to see anything coming out of prediction markets as valuable, especially not on a scale that would counteract their destructiveness. Like, polls are basically equally accurate, and there is zero benefit to anyone to know that there's a 76% chance that Trump will say the word "historic" during his speech Thursday.