(I think we may contest the term 'hoarders' for people with lotsaboox, hmmmm?)
In most of those cases I think we do see a real love of books, though I'm not sure about Hearst and whether 'ostentation' was not on his mind rather than use?
In some cases those appear to be the personal libraries that have fetched up in public collections, and one wonders whether there was a certain amount of weeding and selection at the point of accession. (I'm not saying that Houdini or Arendt also had vast collections of pulp westerns or school stories or whatever, but I'm not ruling out that choices were made at some point.)
And indeed, while calling your private collection 'the Library of the History of Human Imagination' is indeed quite a long way along the pretentiousness scale, I look at that picture: 'It has three levels, a glass bridge, floating platforms' and feel a certain covetousness.
And even if it's ponceyness turned up to 11, it's not as cringe-making as this, which crossed my radar pretty much on the same day: Meet The App That Revolutionized Book Reading For 2 Million People
We sort through the approximately 2,200,000 books published worldwide to find the best nonfiction books out there. Then, our subject specialists, writers, and editors identify the key ideas from each of these hand-selected books and transform them into smart, useful summaries of insights we lovingly polish and refine until they are nothing but the absolute most essential elements of the writer’s main ideas. We do the filtering for you, then we share those ideas with you the way your dream-friend would.Tonstant Weader called for a stiff drink.
*'Twenty-two acknowledged concubines, and a library of sixty-two thousand volumes, attested the variety of his [Gordian II's] inclinations; and from the productions which he left behind him, it appears that the former as well as the latter were designed for use rather than for ostentation.' Edward Gibbon, The History of the Decline and Fall of the Roman Empire, Vol I.