Because the purpose of them is to accurately predict events. People often get better at accurately modeling reality when money is on the line. Prediction markets are designed around the idea that you can best make money if your predictions match reality, so if you bet something that doesn't match reality, people have a direct financial incentive to model reality better and take your money. Some people are absurdly good at it. The net result, in theory, is a financial incentive to get accurate answers about the world.
"Partisan Bias in Factual Beliefs about Politics," Quarterly Journal of Political Science 10(4), 2015.
Consider, hypothetically, that you need to choose between a couple of different possible strategies for solving a problem. (Or, choose how much to invest towards each strategy.)
The vision of people who believe strongly in prediction markets is, for instance, that you could have a prediction market for "if we replace our CEO, will our revenue be higher in X years than the counterfactual where we kept our CEO?", and use that as input to the CEO's performance evaluation. Because people have to put their money where their mouth is, if you believe that a market is incorrectly priced, you can go make money on it.
Whether this works in practice remains to be seen, but it's an interesting vision.
Maybe Kalshi should charge fee for services rendered to the company who wants the prediction, rather than a fee for each contract then. Since you know, they’re providing a valuable service and not profiting on gambling
"Partisan Bias in Factual Beliefs about Politics," Quarterly Journal of Political Science 10(4), 2015.
"You Cannot be Serious: The Impact of Accuracy Incentives on Partisan Bias in Reports of Economic Perceptions", https://ideas.repec.org/a/now/jlqjps/100.00014127.html