So, if the game is good and (!) popular enough, it will sell enough. And Civilization IS very popular. 2K will make enough profit and we will see a Civ VI.
And people, who leech every game, never buying anything, will never be customers. There is no harm in private file-sharing.
Yeah, but there's middle ground between people who always buy and your people who leech "every game."
How big is that middle ground? Who knows? Simple fact remains that if piracy was impossible then sales would increase. I just question whether they'd increase enough to warrant the witch hunt.
Of course, I think many publishers question that as well. Their fear isn't lost sales now, it's an increasing acceptance of piracy, combined with an increased ease of piracy, turning more people into the "leech every game" type.