After years of working in tech I feel like I have pretty good insight into how adtech and SAAS works.
With Apple it's another story. Clearly they have an extremely good business model. Perhaps the best one if you base it on Market Cap.
Is it the integration of hardware and software? Focus on Product? App Store Tax? Ownership of supply chain?
I suspect some combination as well as other factors I don't understand. I tried googling for a stratechery article or something on this but I couldn't find anything that made me feel like I had a good working model.