People will pirate pretty much anything, as long as there are people who are willing to crack and people who are willing to download. There's nothing you can do about it.
The scale of piracy, however, is highly dependent on the quality of the pirated version compared to the original. As long as you do everything you can to make your paying customers happy, there's no reason to worry. Business models based on DRM, DLC, etc. that do nothing except annoy your players, will see a higher piracy rate simply because you made the pirated version that much more better than what you sell.