From a productivity based perspective: The older you get the more it would seem to make sense to use the knowledge you have, rather than to invest heavily in acquiring new knowledge. So what you read would become less important.

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As for why read sci-fi? Well, there's a lot of bad sci-fi out there. At its best it represents interesting explorations of the effects that changes in science, context, and or very other social structures can have when they interact with human societies - and in that much perhaps tells us something about ourselves and where we might be going. Accelerando probably falls into that category, Blindsight would be another, Dune.