Steam is a great example. For years the big publishers had been whining that piracy was destroying PC gaming. Then Steam came out[1] with reasonable priced games, awesome sales and no hassle updates and it is a huge success. There are countless of people who formerly pirated games that now buy a lot of games through Steam.
[1] Ok, I didn't go quite like that.
Another thing to consider is that pirated copies can be lost sales to someone OTHER than the owner of the pirated material.
Suppose I would like a game to relax with. I'm willing to spend up to $20. I see a game that I'd like but it is $50--so I pirate it. Let's assume that if I could not have pirated it, I would not have bought. $50 is simply off the table for me.
We can't reasonably count my pirated copy as a lost sale to the maker of that $50 game.
However, if I could not have pirated it I would still want to have a game. I would have probably found an older game that I could get for $20, or perhaps picked up an indie title or two.