My doctoral work was with the Yucatec Maya in southern Mexico. I spent about 5 years, off and on, in a few small villages. Every once in a while I would meet a so-called "expert" in an airport, or in Merida, the only real city in Yucatan. They were never someone I had heard of in my work. My way to test their qualfications was to smile, and say something extremely offensive in Mayan.
Not one ever passed the test.
These "end of the world" phonies are in the same class of exploiters.