> Earning multiple billion-dollar fines is not serving shareholders.
Correct, and until Apple is threatened with fines, I believe they'll continue doing this until it no longer serves them.
I don't find the tantrums to be the cause of the plateauing, I think they're a response to it. The iPhone is their #1 money-maker (by a massive margin at that), and the smartphone market as a whole has been plateauing. That's why we've seen a shift over the years towards services, which is their #2 money-maker now. When the DMA strongly affects both of these revenue streams, tantrums will ensue.
I'm not agreeing that what they're doing is correct, and I think it's shitty for a company that I consider the reason I got into the dev/design space to begin with to start acting like this. But I do see some business logic behind why they're doing what they're doing, even when it goes against what I know is correct.