How much time and effort may have been put in?

[RobGea]

 I struggle to think of instances where someone made a book that wasn't either for profit (i.e. professionally), for practical reasons or for religious reasons.

Here are 2,

Charles  Dellschau ( 1830 – 1923 )
was a Prussian-American who gained posthumous fame after the discovery of his large scrapbooks that contained drawings, collages and watercolors of airplanes and airships.
.https://en.wikipedia.org/wiki/Charles_Dellschau

Henry Joseph Darger Jr. ( 1892 – 1973 )
was an American janitor and hospital worker who became known after his death for his immense body of art and literature.
.https://en.wikipedia.org/wiki/Henry_Darger

I am not trying to be contrary , it just looks that way 
 but  yes, it does seem to be a rare phenomena.