So there are several intertwined things which bother me about the "these are good because they let people hedge" argument, which I'm having a hard time disentangling here. However, at least one facet is this: The new shiny betting-market can be an inferior form of hedging. (Mankind has a lot of prior-work in this area.) This is especially true for any kind of hedging we're supposed to feel lots of emotional sympathy for.

For example, statistically speaking Iranian Dude might be better-off using their bet-money for targeted purposes, like stocking up on imported durable goods that may become scarce, ideally ones that would have resale value even if nothing catastrophic happened.

The convenient online prediction-casino doesn't require people to have more than a general sense of worry to place a bet, but that also limits how effectively anyone can defend themselves. If you're worried about famine, better to have a payout of food than a payout of cash that won't be able to buy anything.

Which is also hardly imaginable.