Why would Apple want a foundry years behind anything TSMC is doing?

For the same reason they would want a modem business years behind anything Snapdragon is doing.

Apple aims to design its own modems and retain ownership of the intellectual property. Apple is not in the business of manufacturing. its not the same reason

Well a long time they also weren’t in the business of designing silicones but here we are. Apple wants control in every aspect.

Apple is mostly selling mobile devices, so power efficiency is very important. Which means they need cutting edge TSMC nodes. For Nvidia, being server based, power efficiency (electricity cost) is less a concern I believe.

That was definitely true when the iPhone first came out. I don't know if it's true now. Given the average age of an iPhone/iPad keeps going up and up I don't think 90% of consumers are particularly bothered about it. I certainly would doubt that they would lose market share over it if their power efficiency stagnated for a couple of years, at least on an 'iPhone 16e' style chip.

For Nvidia that isn't actually the case at all. It's not electricity per se which is important, it is heat. The new(er) GB200s require liquid cooling because they put out so much heat. Virtually 0 datacentres have liquid cooling to each rack, so rollout has been extremely slow (basically have to build new datacentres from scratch).

The problem Apple has got is they are far, far too reliant on TSMC. It may be worth Apple buying Intel just as an insurance policy. It would be less than 3% of their market cap.

If TSMC goes down/decides not to serve Apple in the future (eg NVidia buying up literally all of the capacity because their products are so much more valuable than Apples)/some other TSMC related black swan event, Apple is close to toast. They get 70-80% of revenue from hardware and could end up with no hardware to sell. Every device they have cannot work without TSMC.

A great book on this btw is Apple in China by Patrick McGee.

I think you have it backwards. Because iOS/macOS can run fine on what Intel fabs can make right now, Apple is not totally dependent on TSMC. In the worst case scenario, they will simply buy all the capacity from Intel, they have enough cash to do so.

Nvidia on the other hand need the latest tech to squeeze the most performance out of their chips for AI companies.

But Intel don't manufacture any ARM mobile SoCs that would be suitable for iPhones and iPads? It's not just a case of "upload A18 design, press print". It is at least a year or two of getting the processes up and running and validated.

So if TSMC went down tomorrow, you can't exactly phone Intel up and say "hi we need 1billion m-series chips a year, starting in a few weeks?"

If they owned it they could start doing that in the background.