Eight-year-old readers want thicker worlds — full middle-grade series, deeper characters, first big themes — while non-fiction serves the specialist obsessions. Choice stays theirs; the shelf just gets deeper.
At eight, the reading appetite (where established) wants immersion: longer books, continuing worlds, characters with real interiors, and the first brushes with big themes at survivable distance.
The competition for eight-year-old attention is real; reading's defence is friction asymmetry — the bedside book versus the negotiated screen, the everywhere-book versus the not-everywhere-tablet — and the household default patterns doing quiet heavy lifting.