because you'll absorb more information. how? when reading a paperback book, you can annotate, which you cannot do with an online book. and for me personally, there's just something so magical about the smell of the glue and paper and the feeling and sound the pages make when you flip them.
Its better to read paper book because paper bookis the exact words that was in the book and online books is tooken from the papers and sometimes its changed into someone elses words and not the way it was before.