"However, copyright is a type of intellectual property, an area of law distinct from that which covers robbery or theft, offenses related only to tangible property. Not all copyright infringement results in commercial loss, and the U.S. Supreme Court ruled in 1985 that infringement does not easily equate with theft."
Theft implies ownership. Even if you buy the game, the company or library host you bought it from doesn't consider it yours. So why would pirating a game be ownership, or "theft," either? Companies say what's in their best interest, money. Ownership, especially of digital media, is a social construct. Writing a file onto your disk is not stealing, as it implies limited supply. No product should have infinite profit, it should be relational to labor not money.