Such books may exist mainly for signalling status, signalling "I can afford to spend time on useless endeavors". Like a whole university degree in literature, only more condensed.

Presumably it works well because it really is extremely time consuming to read those books. The only question is how hard it is to fake having read them (how many details do you have to remember, how many details do other readers remember so that they question you about them).

Thinking about it, perhaps a degree in literature is actually an attempt to fake read all those supposedly important works (you may often only read summaries and learn to bullshit about literature).