Just to give an example, a game called Sins of a Solar Empire famously shipped with absolutely no copy protection at all and still sold 500,000 copies in a market that is absolutely rife with pirating (PC gaming). The CEO of the company that published it gave quite the treatise on the difference between a "potential customer base" and a "potential user base." Some people who will be users will not pay money, no matter what. You can't attempt to stop those people from pirating something. The more difficult your protection, the more likely a scene group is going to try and crack it just for the practice and bragging rights anyway.
His whole approach surrounded marketing to your potential customers by only offering paying customers support, making it very convenient to purchase the product (online distribution), offering frequent updates to ensure the product works smoothly. Basically, making the end user experience as hassle free as humanly possible - the complete opposite approach of big publishers like EA, who have created an enormous community backlash by limiting installs of their software and the like.