By pirating a book, you are stealing. You're taking something that the author (plus the editors, marketing team, literary agents, and others who are behind the novel) put months into making and that something is the way they make their money.
So why do people pirate books? Well, there are a few reasons I came up with...
1. They don't want to spend money
2. They don't want to wait for a book's release date
3. The book isn't available in their country
As for #1, there are legitimate reasons for not having enough money. Books are expensive, especially new hardcovers. But that's why libraries are so fantastic- you can take out books for free! There are usually e-book copies on top of print copies! And if your library doesn't have the book, you can always put in a request. (Of course, there are libraries who don't have the means to fulfill all the requests, and that does pose a serious problem to which I honestly don't have a solution. I do know that in my library system, if your branch doesn't have a book, odds are another branch in the system will.) If the library option doesn't work, ask to borrow the book from a friend or ask for it for Hanukkah/Christmas/your birthday or enter a hundred giveaways online... the point is, you can get books without breaking the bank and without stealing.
As for #2... it may sound harsh but, tough. Sometimes you'll get lucky and you can win an advanced reader's copy or even receive one from the publisher. But when it comes to big books (books like Veronica Roth's Allegiant or Michelle Hodkin's upcoming The Retribution of Mara Dyer), advanced reader's copies aren't even made since there's already buzz surrounding the book! That means that all fans have to wait for the release date and, really, if you're supporting a beloved author, you can wait a few days. The book will be just as good on the actual release date as it would be the week before... it will actually feel better because you won't have piracy on your conscience.
#3: It stinks that the book isn't available in your country. HOWEVER, there are ways to get the book that don't involve piracy! The Book Depository, besides having great prices and a large selection, ships worldwide for free. Curious to see if your country is on the list? They have over a hundred that they ship to, so I'll just link you to the list.
People who pirate books obviously love to read. Logically, then, they want authors to keep producing books so that they can keep reading them. The only way to guarantee this is to actually buy the book (or to borrow it from the library). But piracy? That means no money which means the publisher has no incentive to continue to work with the author and I know no one wants that.
So what is your solution to book piracy? Is it ever okay?