I found the one to write 80 books very quick and easy to achieve. They don't need to be written by one sim.
I made 8 Sims who had suitable traits - can't remember them all at the moment - but they were traits like couch potato and bookish type traits.
I put them into a house with a big room with at least 8 desks with computers and set them to work writing 10 books each.
They had beds and other minimal requirements for survival and they sat in this little house on an island in Isla Paradiso. In the end some wrote more books and others wrote less but between them they did the 80 books and the badge was achieved and I didn't play with them again. They are still in my library though. I made two households of 4 sims and merged them into one household.
