Update, September 25: As it turns out, that European Commission report found that piracy actually increased the number of legitimate sales of videogames.A European Commission report on the effect of piracy on the legitimate sales of films, TV, books, music, and games has found that, eventually,
I would imagine a considerable number of people use games piracy as a form of demo, since they’re very rarely available anymore. Combining that with a lot of people not being able to afford the games they were pirating even if they did want to pay for them, I’m not very surprised that piracy is more of an advertising boost to games than a hindrance.