People desperate for a spiritual connection to anything will shell out money. If it isn't for a fake Indian, then it's for another exploiter. They don't/can't/won't understand that true spirituality or religious belief is not easy. Those things can't be donned and doffed like this month's fashions.
Blame our school system, to some degree. What do students learn about other peoples? I'm sure that many still graduate high school thinking that Aztecs and Mayans are all dead, and with only the haziest (and politically correct) notions of how Eurowhites and Natives interacted historically. Some of them have equally hazy ideas about African and Asian peoples. (A bookstore clerk of Korean ancestry told me that a young woman once asked, "What Chinese are you?" She apparently had no idea that there's more to Asia than China.) Hell, they barely have any idea of United States history, never mind European history. Which is why books that blather about Atlantis, Jesus as ancestor of the Merovingians, Lemuria, and secret codes (all in one volume) sell well enough to recoup publishing costs.
Another reason some people fall for this crap is that the airwaves are full of Christian extremists blatting one-size-fits-all, feel-guilty-about-living, get-right-with-Jesus-or-you-will-go-to-hell crapola. How many people outside of theological circles know the arguments and discussions that go on among the clergy of the various denominations? That there are evangelicals who have no problem with the findings of science, or who loves whom (as long as it is love, and not exploitation)? Most of us only hear the likes of Pat Robertson and the late Jerry Falwell, because they make for great sound-bites.
Anyway, when one's only experience with religion is guilt, someone who offers freedom from guilt is very appealing. And in our instant-results culture, the idea that a weekend (or two, or three, or four...) can turn everything around seems very plausible. ('Yes, and if you come to my church, I will exorcise the demons named Greed, Lust, Anger, Gluttony, et al. from you. Now, you may need to return from time to time, but we'll reserve a barf-bag for you.' That also happens.)