In my opinion, the only case where there can be too much reading is if it starts affecting your Job, health, family relationships and social life.
We all need a balance in our life and focusing too much on one element of our life to the detriment of other aspects is not good.
Personally, I had read 1 or 2 books in my life (I had to because it was related to school homework) until 1 1/2 years ago. Then last year, I hit an all-time record of 12 books.
I will continue increasing that number (I purchased a
Photo Reading course to increase my reading speed) every year.
I read Personal Development books and biographies.
René