The same argument applies to DRM and piracy. DRM only disadvantages people who want to consume content legally. Only one person has to bypass it (be it through cryptographic or software failings or the good old fashioned analog hole ala telesync) then upload the resulting unencumbered media file to a piracy site. As a result, it's not just cheaper, but also easier and more reliable to steal media than it is to buy it…
Drm is not targeted at the hardcore pirate, it's targeted at a potentially larger percentage of people who would be tempted to get the thing for free if it was easy. Drm may be circumventable, but any complex set of steps for doing so is enough to deter that target audience.
-Most people’s grandfather
(I’m not saying these things are equal — just that this concept and the old saying share a perspective on securing things.)