http://www.tweakguides.com/Piracy_1.html
This guy goes over piracy very thoroughly. People rationalize and believe that people that pirate play as a demo. Well, they might. Their friends might. But the vast majority of pirates don't pay the developers unless they get sued.
Crysis was one of the most pirated games if its release year, and is pretty high on the list of all time. Yet, Crytek has still developed with PC clearly in mind. Is this how we should repay them? I wouldn't blame Crytek if they decide to drastically change their approach concerning the PC platform from now on. I hope that's not the case, but if you can't see how piracy is harming the PC industry (let alone the moral, ethical, and legal issues,) you are blind. Yes, games can be successful when there's piracy. However, it discourages developers big and small to innovate or take risks.
I could go on, but it's late. I hope that the majority of PC gamers are honest and refuse to download the torrent.