"If the game gets pirated heavily, if it's a good game that people really like, they're going to either buy it eventually or they're going to tell other people about it. Either way it's just going to come back to a sale."
Well, I can tell you about how it was back in the days when Commodore 64, and piracy, ruled gaming. Me, my friends, school mates, etc - everyone was pirating, I didn't know one single person with a C64 that didn't copy games. There were partys where kids could come together and just pirate stuff. People swapped games on the school yards. There was no end to it. I guess you could say that it was somewhat like youngsters does today with music and mp3s. Piracy was normal.
But no. It did NOT end up in a purchase. Never. And why would it? If you're fine with the immorality about piracy, or theft if you like, then there is no single reason to buy a game you could get for free.
And nope, I never bought a game I already had, no matter how much I liked it. The same goes for my friends, and honestly everyone I knew had a C64. If you actually did buy a game people would ask you "But why?? I have it, why didn't you ask me? You could've just copied it from me."
People talking about a great game, super high scores in magazines, etc, never made me, or my friends, buy a game either. It did however made us search for it as a pirated software.
The only games I bought during that time were the few ones that I didn't find as pirated software. Which during about 5 years was about 10 in total, maybe less. Yet, I had about a thousand games in total.
Now, I don't know if it's the same these days. But judging by my friends with PC's who pirate music, movies and games like crazy I'd say that it is indeed exactly the same - if they can't find it pirated they just don't care about it or they just wait a while until it ends up on the net - it never ever seem to end up as a purchase.