Reading a book in the past was, many times, something to do to avoid boredom.
Reading a book today, for the majority of people, is the definition of boredom.
Thus, reading a book feels like a risky enterprise. There's so many stuff to do, however futile, that people don't want to waste their time.
But reading a book is often a rewarding experience, even if the reward only comes years after.
Perhaps a good motivator is to think of it as a skill: the skill of reading books. For every book you read you develop that skill. You may not know what the skill's for, but you know with almost 100% certainty that it is and it will be for something (particularly in the case of non-fiction books).
