Well here's food for thought:

You bought a hard-back novel (lets just say The Girl with the Dragon Tatoo).
You've read it half-way until you get a Kindle as a birthday gift. You buy several novels, but now your limited to carrying 2 large items with you to work (reading on the train, bus, lunch and between waits). Your friend, having bought the novel as a digital copy, lets you illegally copy it. You now just skip to the appropriate section, and now can enjoy whatever novel you want to read conveniently and portably.
Alls good, but you've still stolen someone's IP and they're right for financial gains.

.... .... .... Take it away boys