My worry is that social media surveillance could be combined with Polymarket to tailor bets to individuals.
This could be very subtle. You don't really need your punters to always be wrong either. Meaning that sometimes they'd win at the expense of other punters with the illusion they can make money.
You just need them to be wrong, say, 15% of the time and to keep coming back compulsively and consistently over time. The longer the better.
If you're ever around fruit/slot machines you'll notice that they do payout and when they do they make a lot of noise. That hides the fact they slowly cream off a percentage of the money that goes in. In the UK the legal limit is around 30%, keeping it low for new gamblers and ramping up when they're hooked.
With detailed information about punter's lives and no regulation you can weaponise that.