The point is that even a weak DRM system like Kindle's is sufficient to keep most people on the right side of the line. It doesn't have to be perfect.

I don't believe that DRM deserves the credit because I have yet to observe any such deterrent effect, while conversely, I have heard of many who turned to piracy due to feeling cheated by DRM.

I'm just curious, but have you ever observed anyone give up and buy something because they failed to pirate it?

What did you fail to pirate?