I think his consistent track record of apocalypse failure predictions (and then lack of examining his failure) is made even weirder by how good of a thinker or writer he comes across in some of his fiction.
I started reading the Laundry Files, and was shocked by how diverse his knowledge is, and how well he understands some aspects of the world (bureaucracy, the nature of horror writing, state intelligence apparatuses).
He seems to be far more intelligent and knowledgeable than the average human. So why the incredible lack of self-awareness when it comes to predicting the end of the world?