The answer is stupidly simple but only touched on briefly in the article. It is the fees and the limits bet sizes combined. Let’s take a simple example, which

The answer is stupidly simple but only touched on briefly in the article. It is the fees and the limits bet sizes combined. Let’s take a simple example, which is Donald Trump‘s current odds of winning the Republican nomination. Predictit currently has this at $0.92. Realistically I think the odds are higher. Not 100% but higher than $0.92. The problem is that the maximum I can bet is $500, so that’s 543 “shares” that I can buy. And I’ll make $0.08 on each share if he wins, so that’s $43. Then when I withdraw my money I will get a 5% fee, so my initial $500 turns in to $516. Oh, and then I have to wait until primaries, and for it to actually pay out. And there IS a non zero chance trump loses. Very few individuals will care about turning $500 into $515, so this bet makes sense. And since you have a cap on bet size, no institution will care either. sounds like a rational market to me.