I feel like everyone should have seen that coming.
Do they have no banking system? Handing a few young kids giant bags of cash like that seems... kind of irresponsible and asking for every sort of trouble.
(Like, it's the sort of thing I'd sometimes comment on jokingly in passing and just treat as lazy writing, but today it seems the consequences are real. This isn't even the worst possible outcome; who knows what else could have happened if they'd gotten robbed just carrying around those bags right after this, with nowhere to put them...)