Good stuff here. These groups are just making money by posting photos (hopefully with a profile link) but then trying to charge anyone who asks or even emailing people about an "awesome deal on posts".
It's interesting because no one used to make money stealing your 640 pixel online image, but that's not the case on Instagram anymore.
I think the sharing is fine as long as they tag the photographer's account and give clear credit.
Sounds like it takes a crowd to reply an offender if you find someone stealing images though - the risk of losing the account is very real. That was a Hilarious story, Joost!