Basically, it's like locks on car doors. If a professional thief wants your stuff, he's gonna get it. The locks are there to keep the honest people honest.

A fair enough metaphor.
To extend it slightly: I have to circumvent my car locks about once every 5 or 10 years when I lock my keys in the car. With DRM, it's like having to circumvent the locks every time you want to park in a different garage....