Very interesting. From Wikipedia:
Langan's support of conspiracy theories, including the 9/11 Truther movement and the white genocide conspiracy theory, and his opposition to interracial relationships, have contributed to his gaining a following among members of the alt-right and others on the far-right. Journalists have described some of Langan's Internet posts as racist, and accused him of veiled antisemitism.
I wonder how a leftist would explain this. They always tell us that anyone who holds any of these views is a knuckle dragging idiot who likely lives in a trailer park. How would they explain the smartest, or at least one of the smartest, men on the planet believing these things to be true?