I'm no business expert and Apple is of course in a unique position, but owning your own fabs has rarely worked out long term. They require eye watering amounts of CAPEX that needs to be amortized over a timeframe that's longer than apple's products. Today's bleeding edge fabs become tomorrow's "cheap" fabs that pump out chips that don't need to be bleeding edge for the components that go into everyday products like microwaves, cars, etc.

One of the reasons Intel fell behind is that they couldn't give access to their competitors for business reasons, and therefore could never scale as high as TSMC could.

There are many other reasons, but accounting is a huge one. Unless there is a huge ROI or something else we don't otherwise know, I don't see Apple adding such expensive deprecating assets onto their books as chip fabs.