Apple has always spent money in development. The thing with Apple is they always let development be their guide, and budget is never really a consideration, until it because time to make decisions on a development roadmap. Mark Rober, and actual ex Apple Engineer has talked a lot about this.
Modems was Jobs. Tim cut it because they went far enough and couldn’t Improve on Qualcomm and more efficient to pay for it. Efficiencies.
Sapphire Glass was also a Jobs thing. Jobs wasted billions with nothing coming from it at all. Zero, nada.
Operation Titan was a bust but lead into Apple Carplay which is often the single most important thing that many people use when deciding on a car. I certainly won’t buy a car without it. They always get a lot of tech come from development. Vision Pro spatial computing is another. So it has also been very useful. But nevertheless, Cook stopped it.
Apple TV+ is still going and if they are making budget cuts, it’s just budget cuts. IF they have made cuts, they are being more wise with their spending.
So, I’m not sure where he has 'lost his way' because he has been consistent all the way through. Jobs was wasteful, but with a purpose. Cook let’s things goes but always, always reins it in at some point.