It's hard to read old books sometimes. Unless you grew up doing it you just simply don't understand character intentions. Reading a Dostoyevsky book it's hard to relate to characters or even understand the outrage in a lot of scenes.

If you don't know your history well, the whole setting for the Count of Monte Cristo is confusing af. So you now need to read up on the fall and rise of the monarchy and Napoleon, and his exile etc. Also a lot of words are just foreign to most people.

Where as reading a book written recently it's just way easier to get into it since it's written in the context of our collective memory (if that makes sense).