That 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.
They can already grab your binary by using third party tools or by using the Apple Configurator from what I’m seeing.
TIL: iPhone backups on computers stopped including full ipa’s back in 2017…
They're encrypted using FairPlay, so you need either a jailbroken iPhone or a "jailbroken" (SIP bypass while SIP is enabled) Mac to decrypt them. The former will stop being possible soon enough, the latter will likely remain possible for quite some time.