alt Hacker NewsThat couldn’t be the reason. 90% of App Store revenue comes from in app purchases of consumables from games. This came out in the Epic trial.
The rest of the most use apps are front end for services where the app is free. There are very very few one time app purchases on iOS where pirating would make sense
Piracy is not the only risk when someone grabs your app binary, but also cracked versions with ads removed, or subscription checks disabled.