It's the fault of the entire ecosystem that a company is targeted by pirates when it chooses to make a small number of high-quality TV shows with excellent production value and put them behind an expensive paywall only available to people with cable TV subscriptions?
I mean, I understand the rationale of HBO in accepting the cost of piracy in order to maintain a lucrative symbiosis with cable affiliates. But I'm sure they recognize that in doing so they cause a significant amount of piracy, and it harms everyone in the TV business, not just HBO.
There's basically two driving forces behind piracy. One is price, but there is a good argument to be made that people who pirate because they couldn't otherwise afford to pay otherwise don't actually affect the bottom line very much. The other is universality. Ten dollars a month to a usenet provider or VPN service will give access to every single major movie, TV show, and album within a few days of release. It comes in multiple DRM-free formats, and can be played basically anywhere.
So long as piracy has a distinct service and price advantage over HBO, they are encouraging piracy. And the worst part for TV producers is that there is a negative network effect: once someone spends the opportunity cost to pirate Game of Thrones, the marginal cost of pirating something else goes way down, and services that do compete favorably with piracy from a service perspective like Netflix and iTunes suffer as well.