There is also a strong signaling effect.
For better or worse, which books people are reading (or say they are reading) is often used to determine which "camp" they belong to. People who took the time to read Musk's biography are viewed slightly differently than those who chose not to.
IRL, discussions of the contents and ideas tend to be superficial.
When I'm asked what books I'm reading, I always answer honestly, but rarely mention a title that's been published in the last 30 years or so. For some reason, people seem to be more comfortable deeply discussing older works.
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