Reading 1000 books before kindergarten is actually not that difficult -- many children do, and more. If they get one book read to them from ages 1-4, they will have more than 1000 books by the time they enter kindergarten.
But imagine a child's thrill when she hears the 100-book mark she's reached! The 500-book! The 1000-book! The 2000-book! Such a number!
She can't help but be impressed with herself -- even if her counting skills are weak.