I'm sad to say that I've been guilty of downloading and reading illegal eBooks from torrent sites. I know for a fact that many software developers do this. At each place I've consulted, I've met developers with literally an entire Borders collection on their hard drives (excuse the pun).
Being an author and a generally honest guy, so I'm not very proud of this. But, it has made me realise one thing:
IT'S NOT WORTH IT!
It's not worth downloading dodgy eBooks from torrent sites because you don't get the real value from the book. I believe the real value of a book lies partly in it's physical form.
An eBook is great for reference or high level scanning, but a paper book is far easier to actually study.
I can leave a paper book around the office or house where I'm likely to pick it up, making me more likely to read it. The book itself can become it's own bookmark in your life - a visual reminder to continue reading.
e-Ink readers like the Kindle are cool (I have an IREX Illiad), but in many ways a real book still out-performs it. With a real book, the pages fit perfectly and I don't have to worry about it's batteries running out, or remembering to charge it up.
I tend to read paper books two or three times, mainly because they occupy shelf space in my study, which is where I look for reading inspiration. I also frequently pull them off the shelf for looking something up. eBooks don't lure me in this way, so they get read less often.
I can annotate books with a pen or sticky notes easily, without having to worry about losing my annotations or synchronising them across devices.
All in all I'm pretty happy with the decision that, if I want to read about something, I'm happy to pay the money and buy the paper book to get the full value from it's contents. Time is valuable, and I'd prefer to pay cash to increase my chances of soaking up the authors wisdom.