Ignoring the fact that this probably the first pyramid scheme in that world so they wouldn't already be aware of it, Pyramid schemes have always been effective scams because they seem like a good plan until it's too late to back out.
They target people who are already down on their luck and desperate, they promise them moderate wealth with the chance at something greater, and they provide plan that seems like it will work. They also frequently parade out early adopters whom it actually DID work for. Once you're in, it is very hard to get out without destroying yourself financially.