A few days ago I was half-asked exactly why I read.
A few minutes ago I was putting together a new Abundance of Quotes post and was looking through my Writings on Writing quote book, and two of the quotes I found described the answer-I-never-gave to that question fairly comprehensively, so I thought I'd make them into a post of their own.
"The man who adds the life of books to the actual life of everyday lives the life of the whole race. The man without books lives only the life of one individual." - Jessie Lee Bennett, 1923
Which pretty much sums up why I read. When I was first learning way back in the Time Before My Memory Begins (or close enough to it), I wasn't terribly enthusiastic about it. Then my dad said to me something like "Books allow you to explore whole new worlds." -- and I was hooked.
And here are the other reasons: "The book is the thing. Literature was meant to give pleasure, to excite interest, to banish solitude, to make the fireside more attractive than the tavern, to give joy to those who are still capable of joy, and--why should we not admit it?-- to drug sorrow and divert thought." - Augustine Birrell, 1896
The only other reason would be the exposure to ideas-- books make me think about things I otherwise would not and/or present new perspectives, which I suppose could be sorted under the first quote.
So there you have it: exploration/thought, escapism, and pleasure.