Today I was sent a link to a forum post where someone speaks enthusiastically about how much they've enjoyed some books of mine (among a number of others), and offers to share the ebook versions with other forum users for free.
I don't know how certain people so consistently fail to understand this, but here it is. Books (including ebooks) are as good as they are, and cost the amounts they do, because a lot of people's time -- authors', editors', illustrators', publishers' -- goes into creating them. You're not paying for the paper and ink that make up the book, or the server space the ebook is held on, you're paying for the time -- sometimes months or years -- that people have spent lovingly working on this thing you've enjoyed reading. To then distribute that work for free -- thus ensuring that the publisher's sales and income remain low and that the money they have to compensate their authors, editors and illustrators remains limited -- shows a degree of thoughtlessness and contempt for those people and their work that's simply staggering.
Other people's work is worth your money. If you won't pay, you don't deserve the benefit of the work. It's that simple.