Is it the most elaborate hoax ever?
Well, according to this article from Scientific American, it very well could be. In fact, it might be the most famous con, too. Experts have analyzed this manuscript, found by Wilfrid Voynich, an American rare-book dealer, in 1912, but haven’t been able to come up with either the code or language in which the book is written. One theory is that English adventurer Edward Kelley may have created the document to defraud the Holy Roman Emperor, Rudolph II who reportedly paid a sum of 600 ducats (about $50,000 today) for the manuscript.)
The article goes into the details, but it seems quite plausable. So, I guess conlanging can be profitable after all!