Some great thoughts here from Scott Berkun:

It's good to buy books even if you don't end up reading them. Why? 1. It supports authors who made something that interests you 2. It signals to publishers there is market for works like it 3. We should be generous about investing in our potential interests even if they don't all pan out

Here's a phenomenon I'll add to the mix: things (and people! and places! and experiences! and ideas! and tools! and technology! and music! and art!) may enter your life at a time where for whatever reason you're not ready for them. We then feel guilty for not picking that book up, or convince ourselves it wasn't worth reading anyways. I've seen it with the stuff (OH GOD THE STUFF) that has entered my daughter's life. "Eh, she's just not into it. Oh well, it was worth a try." But then, one day...BAM! That thing is her new favorite thing. The game that's been collecting dust since she was 4 is now suddenly her favorite thing. There are many books on my shelf that sat unread on my bookshelf for years. Until one day...BAM! My life circumstances suddenly lead me to rush to the bookshelf and grab that book (that I knew was there, that's important!) and devour it with my full self. Be careful not to make hasty decisions about anything or anyone that enters your life; you might just not be ready for them yet.