Prediction markets perform the valuable function of information aggregation, at least in theory. When there is a financial incentive to make a correct prediction, the market should converge on the probability an ideal observer would assign to the event.

Of course in practice, there are issues like low trading volume, market manipulation, etc. And whether or not a particular market is performing better than, say, super-forecasters or experts in a given field is an empirical question.

That said, it seems a bit excessive to dismiss prediction markets as merely gambling platforms that add no value to society.