1. The purpose of DRM is to prevent people from copying content while allowing people to view that content,
2. You can't hide something from someone while showing it to them,
3. And in any case widespread copyright violations (e.g. movies on file sharing sites) often come from sources that aren't encrypted in the first place, e.g. leaks from studios.
It turns out that this argument is fundamentally flawed. Usually the arguments from pro-DRM people are that #2 and #3 are false. But no, those are true. The problem is #1 is false.
Only related tangentially, but I find myself breaking DRM simply because it is such a colossal pain otherwise. I didn't really care about DVD DRM as it was broken easily so I never created rips that I uploaded to the internet. I could pop it in and the software would do the magic for me. But for Blu-ray, most decent media players cannot read them. Even with libaacs, newer discs are often unreadable. So I find my self dumping keys, decrypting the contents and copying them to a BDMV structure, encoding them and then finally enjoying whatever I paid for. Which is faster than trying to get it to work normally.