• Because they can.
  • Because it is easy.
  • Because they are poor.
  • Because DRM.
  • Because they want to own the software.
  • Because they want to bypass X.
  • Because censorship.
  • Because the official service like e.g. Netflix flag their country and or VPN, tor etc.
  • Because privacy and or security reasons.
  • Because they do not want to agree in the EULA.
  • Because they contacted the developer and he refused to give a discount or work something out.
  • Higher download speed.
  • Less to download, repacks etc.
  • Original software is not any more downloadable, officially.
  • Archive reasons.
  • Data hording reasons.
  • Because modding and sharing reasons, which would violate any EULA or agreement anyway.