Simple remove DRM, since those who pirate it will do it never the less. Still to date, I haven't heard of a game, where its DRM has stopped Piracy. Even the most hardcore DRM's are craked/worked around.
Even the games which require a online connection has been seen cracked and what not.
Even more offen if your game have some draconian DRM which provides problems for the legal user, to a point, where it would be easier just to go pirate it instead.
Gabe Newell talked about this some time ago. He pointed to the Russian marked. For many years it has been know in the industry, that Russia and the east Europe countries has been a really bad game marked, due to the extreme level of piracy.
But when they launched Steam there, and gave the customers a easy, convenient, legal alternative, it became a huge success.
That combination they provide with Steam (and Origin soon) are a much better way to fight piracy, that we have seen so far.
But my best example will be the first Hitman game. It had no kind of DRM at all... not even cd-key. You bough the game, installed it and threw the cd away. Still that game sold so much, that it founded their studio and gave them the lift-off into being an AAA game developer.
So TL;DR, You can fight Piracy, but that will still be nowhere or you can ignore it and save those money and trouble and use them for a better product or service.
There are tons of better ways to make sure people don't pirate your game, but buys it instead. Give them reason to buy legal instead of give them the impression that the much easier way are to pirate it instead.