I've actually seen this one plenty of times. Kudos for the write-up.

Just using some logic should hopefully make it clear why this is a scam. Firstly, fixed matches are illegal, and why would anyone openly advertise the fact that they are in on fixed matches? Secondly, if there were indeed a professional match fixer, why would they let anyone else know, as that would diminish their profits?

Sometimes greed gets the best of people and they fall for this. But it is entirely avoidable.