Before the advent of the personal computer, computers cost as least as much as a small home. Arguably you could say the computers time was more valuable than the people using them, and people shared them in research and industrial labs.
Both items have become many orders of magnitude cheaper and plentiful to the point of commoditization. eBooks are still competing with hard copy works so the price differential isn't quite there. But once that industry capitulates look for them to drop significantly.
Personally I like the scenario where a friend recommends me a book for $2 that I can purchase for $2 myself vs. him paying $10 and letting me borrow. I like to pay for things that bring value to my life, and in a way he's subsidizing my usage.