They can, they're just not doing anything they couldn't do at a blackjack table.

I don't think you have a real point here, and are just using pejorative language about gambling to suggest one. Your thesis seems to be that only insiders can make valid predictions, which is nonsense.

I'm saying that most people --- and functionally all the people who feel victimized by insiders --- on Polymarket are gambling, not predicting. I feel pretty comfortable with how sound that argument is. I agree that there are users of prediction markets who are neither "insiders" (for whatever definition of that you want to use) nor gamblers, but they're participating with the understanding that they're bidding alongside insiders. And they're a tiny cohort.

If it helps, draw a line between "entertainment" and "enterprise", and use whatever term you like for uses on the "entertainment" side of the line. Either way: it has stark implications for the notion of insider impropriety.

This is just redefinition to belabor your insiders point (which I am not disagreeing with). Non-insiders are gambling, but they are also making predictions, with varying degrees of skill

Some kinds of gambling are truly random (unless they are scams) and no prediction is possible. Other kinds involve some degree of skill and predictive power. For example, people can make predictions on races based on past form, even though the element of chance can't be eliminated. It seems like you're trying to redefine 'prediction' to mean 'anticipated outcome as assessed by the most informed' in order to disqualify the validity of any opinions held by non-insiders.

I get that you want everyone to be aware of how prediction arguments were originally a fun way for experts to drive decision making without writing ever-longer arguments for their position. But you seem to be overlooking the the fact that objections are not so much to insiders disrupting hte prediction market as the impropriety of government officials or their special friends cashing in on military adventurism. Said government officials defend engaging military adventures without consent or even notice to Congress by citing security, yet placing big bets on markets to make a quick profit is highly insecure.

I don't care about insiders cashing on on adventurism. Or, rather, I care about the adventurism, but I do not care even a little bit about the impact of it on gambling platforms like Polymarket. I think I'm on reasonably firm footing when I say that (a) the inventors and popularizers of modern prediction markets and (b) US law doesn't care either.

The irony here is that the one bank-shot argument I'd see in the medium term for "insider trading" enforcement at places like Polymarket is Nevada Gaming Commission-style gambling regulation.