I could be way wrong here. But this is a true story, there were people in an alliance I was once in that used to post scam contracts like that and their rich buddies (dysporoum or technicium moon owners) would donate isk to their noob pilot alts and purchase the contract.
(edit: I’m on a bus and some dude asked for my phone charger… it posted before I finished)
The isk would be transferred back and they’d do the whole Jita local “THX 4 THE AMAZING DEAL!!!” nonsense.
Since there is no real way to verify whether those contracts you went through were in any way legitimate, it’s practically impossible to know what ; if any significant isk was made.
I met a lot of scammers in null alliances and none of them knew how to make isk. They were just bored waiting for fleets and they couldn’t afford the basic doctrine fits of the time. I started to realize (at least the scammers in the alliances I was in) that they were simply the equivalent to homeless beggars and contracts were lotto tickets, very rarely did they ever get anything out of it.
Because of the difficulty in knowing what contracts were real (as in someone legitimately got scammed) it’s very hard to even ball park it.