1. Have fun.
If you don't like the book you're reading, put it down. Life is too short for bad books.
2. Leave a general impression on you.
For example, some books just change your outlook on life. Margaret Atwood's MaddAddam trilogy, or Pierce Brown's Red Rising trilogy, or Scott Lynch's Gentlemen Bastard's trilogy are all great series that take you on emotional roller-coasters, make you change you perspective on life, etc.
Reading makes people more empathic, and kinder. It helps give you different points of view. (https://www.researchgate.net/publication/315838511_Turner_R_...)
“A reader lives a thousand lives before he dies, said Jojen. The man who never reads lives only one.” ― George R.R. Martin, A Dance with Dragons
Presumably you can also get this from film and television?
My gut tells me that film and television is to reading as a snack is to a meal.
> Reading and experience train your model of the world. And even if you forget the experience or what you read, its effect on your model of the world persists. Your mind is like a compiled program you've lost the source of. It works, but you don't know why.
It's almost like placing the dots and then they'll connect themselves later. It's probably inefficient but I enjoy reading and those situations make it worth it.
There's plenty of things to retain in books read for entertainment.