I agree completely that there are far too many religious con men out there scamming people. Unfortunately, in this case, I am going to side with the victims being on the naively stupid. When your exorcists want you to bring all your valuables including cash and put them in a bag for them to be blessed, you are being asked to be robbed.
I have heard of hundreds of traditional medicine and occult rituals that are supposed to do everything from keeping bad spirits away to resurrecting the dead. However, none of them have ever blessed cash before. Most of the time they ask for a sizable payment, and then provide a placebo.