Being rich isn’t really related, it’s that they can still profit while doing this (some people say “sheep” while others say “good products with great integration”), where nobody else can, which makes them rich. ;)
> Well, buying the leading node is big $ that not everyone can afford.
It isn't just that Apple can afford a particular part. Apple funds some of the R&D for that part, the building of the factory (sometimes, multiple factories) that create that part, and will commit to buying 100% of its capacity for years.
They aren't just outbidding others for capacity. They are making long-term strategic partnerships to _build_ that capacity.
> Putting memory on package runs counter to repairability, modularity, etc.
Everything is a trade-off. For traditional OEM integration for desktops and laptops, memory on package would be too limiting. Apple is one of the few companies that can pull it off.
When you're as vertically integrated and rich as Apple it makes sense.