I speculate that it's theoretically possible to build virtually unbreakable DRM into a physical device, especially if the device is designed to resist (or at least detect) disassembly. (Analog re-recording notwithstanding).

I like your point about DRM vs copyright. I guess I've always seen DRM as the "ounce of prevention" that replaces the "pound of cure" that copyright enforcement entails - although distribution platforms like YouTube increasingly reduce that pound to closer to an ounce (at the cost of more abuse). I think your point would be valid if enforcement of copyright was simpler and cheaper; perhaps you've read stories about photographers whose work has been used by large companies, without compensation, usually because the asset was included in projects done by 3rd party contractors. Its very expensive for an individual to enforce their rights. But yes, if the justice system itself were fixed to be fast, cheap, and fair, then I would agree that copyright alone would be the preferable solution.