The high price. The marketing that plays primarily on intangibles. It just all seems to be from a playbook that is well known in the wine world, and has Noka as a precedent in chocolate.
That said, I have no concrete evidence that they're frauds. For all I know, everything they say about their chocolate could be true (which, arguably, would be the best scam of them all; I just can't see a rational argument to be made for a $300 chocolate bar).