"Just as naval piracy is something more complex than "robbing people using a ship" information piracy is not just simply theft, as some opponents commonly claim. The key difference is that while copyright infringement may cause an economic loss it does not appropriate the object or deprive the copyright holder of the use of the copyright. Information is a non-rival good, and its value can change in nontrivial ways by becoming more accessible (e.g. widespread software piracy has probably helped expensive software such as Photoshop and Windows to become standard even in poorer countries).
The concept of ownership is deeply ingrained in all humans, perhaps evolved from territoriality. It can be clearly observed when playing with children, who at an early age become aware that certain toys are theirs and become upset if others play with them. This innate "intuitive ownership" works well with material objects, which tend to be rival goods. It makes sense to have a right to exclude others from the property (since their use is rival) and control how it is used. On a more adult level, we tend to add principles such as the right to benefit from the property and a right to transfer or sell it. If somebody handles our property without our permission we tend to become upset on an emotional level, regardless of any tangible loss. This is also why communal property is hard to maintain: it is non-intuitive, if people have no ties to it they will tend to undervalue/undermaintain it, and if they have strong ties there is a risk of jealousy." READ THE WHOLE ARTICLE HERE