Seth Godin has also mentioned DRM in several of his blog posts. The thing is, it doesn't actually cost us if someone pirates a game. That's because they aren't physically stealing something of value to us, only a potential sale - if they really were going to buy it, and they still can.
And if a game is being pirated it also means the game is being shared, publicized, etc. It's almost a win-win situation, but I think all of us have this little fear of living in a cardboard box on the side of the road saying, "I made that game," as some punk kids walk by playing it and laugh at the crazy guy. Everyone is playing, but no one is paying. (slight exaggeration
)
But even if everyone pirated your game - literally, every one. No one bought it.
If it was good they will still look to you for another game. And you'll make money on that.
The way I look at it is: Piracy is not the biggest problem for an indie; marketing is.