It's just ao insane that a company that's sitting on a massive pile of cash and has been wildly profitable for decades still needs to do this. I suppose the valuation requires more growth, and they're out of good ideas.
According to leaked BOMs, the iPhone usually has ~40% profit margins. It's very likely that Apple Music, the App Store and iCloud all turn >90% margins, which is basically free revenue to shareholders.
So that makes it really hard to make a lot of profit - as the royalty costs grow linearly with your revenue.