SimonG: DRM has always been against the second hand market, not against piracy. At least there it succeeded.
orcishgamer: Touchee, I've always agreed this is the real purpose as well. Just no one seems on board with the idea.
I think it is one of its purposes, but not the only one. If it was only about killing the second hand market, then it would have been mission accomplished on PC for many many years already, and the publishers wouldn't keep complaining about the PC market/users as they still do, coming up with things like always-online DRM, streaming gaming etc.
On the console side, where piracy is far more negligible compared to PC but second-hand market is still alive and well, it may well be the main or even only reason. After all, there the publishers are indeed complaining about the second-hand sales destroying the market, not piracy like on the PC side.