This is a paper from 1993 (freely available here) that looks at various European book-hoarders from the Early Modern period. It lists various types of motivations for why they allowed themselves to indulge in their obsession, with each kind of motivation accompanied by a case study, a closer look at one or more specific individuals.

This was informative and dealt in a straightforward manner with how a familiar hobby works out in society that didn’t have the easy accessibility of books that we do. The text is dry (but that’s a feature, not a bug), but that is more than offset by its focus on Early Modern weirdos. ( )