When you buy something, it is yours. If i buy a hot dog I can eat it, throw it away, even give it to somebody else. If you buy DRM content, you're basically being told that the thing you just legally bought and is now yours, is not necessarily yours. DRM also puts all of the information of hundred of purchases and records in to one place, so if somebody manages to get into this, they'll have million of personal records from purchases. The biggest example of DRM for those who don't know would be Steam.