Take World of Goo. Very popular game. Released in 2008; got a sequel in 2024. Why so long for a sequel? In part, because when they experimented with a DRM-free release, they had a piracy rate of over 90%. Can you prove that's lost sales? No. Would any reasonable person say that is lost sales? Absolutely.
https://arstechnica.com/gaming/2008/11/acrying-shame-world-o...
Ever wonder why mobile games failed, and why every mobile game is seemingly full of ads? The Android piracy rate is enormous (over 60%); and freemium allows money to be earned while denting piracy rates. Let's not forget also why Nintendo went after Yuzu - over 1 million illegal downloads of Tears of the Kingdom before the game even launched. How many do you think paid afterwards?
And before anyone quotes the one or two studies showing an increase in sales from piracy; that ignores the 30+ studies showing a moderate to severe sales impact from piracy, that we also have. Nobody talks about those though, because that's a rather unpopular conclusion. However, you can't pick and choose studies to show it is a good thing.