They're not 'the only ones' in that childish playground bragging kind of sense. If you want one you can buy one from them. It's just business.

Also much of this tech only existed when it did due to their investment in technology development and tooling. Microsoft had dragged their feet on Hi-DPI for years before Apple jumped ahead with retina and 5K and forced them to pull their socks up. Android phones probably went to 64-bit two years earlier than they otherwise would have. With Surface devices Microsoft has come up with some genuinely innovative and forward looking designs and engineering, but would they have done that without the spur of competing with the iPad and Mac? Apple have been single handedly dragging the rest of the industry kicking and screaming into the future, to everyone's benefit. How is that outcome 'evil'?

I think it starts, at least, with simple practicality. Apple products usually sell in massive volumes. When they introduce some new aspect, they have to be able to produce huge numbers of this thing, and since it's new, the industrial capacity to produce at those numbers reliably does not exist. They have no choice but to buy out and invest in all the available capacity, because they rarely release innovations in some small-scale experimental product. They swing for the fences for a mass market home run almost every time.

And they do this so well because they're led by Tim Cook who approaches the big picture in part in terms of supply chain.

I don't argue that cornering the market isn't an accounted-for and desirable side-benefit of this arrangement. I just don't think it's usually the starting point for them.

It’s business. This is all part of the reputation and image Apple wants. Any reasonably managed business will lean into its differentiations. This happens in every business sector at any measurable scale.

Greed sure, but it's also control. Apple has always been fanatical about controlling what the user, seller, repair shops, retail, etc can do with their products. Among other reasons, its one of the top reasons I'll never use Apple computers. I want complete control of my devices, and the ability to break my machines while pushing boundaries. Apple would rather have me locked in to their 30% fee App Store cash cow with apps that require their approval to exist.

I have heard that it might be possible to hack your Mac laptop (using a setting in System Preferences>Security&Privacy>General) to allow it to run code on that isn't from Apple's App Store.

There is no lock preventing you installing non-Apple executable. Theres a warning and such but I install apps from third parties all the time. There are even several package managers, macports and homebrew, that will install userland unix binaries for you.

Where is that setting on the iPhone and iPad?

There isn't one because the iPhone/iPad is a closed ecosystem, whereas macOS is not.

There are pro's and con's to both models; choose the one that works best for you. Even if it's not Apple :)

Brand marketing. It cements the Apple brand as being high quality and Apple products as being better than anything else available, justifying a premium price in the minds of their customers.

It's usually a legitimate justification, too. Nobody else makes hardware this nice, almost as a general rule.

It is not greed, it is ego. Apple as a whole has an ego complex and it shows in so much of what they do. They always, to the point of harping, emphasize the Pro label and premium experience and premium materials. Even their head quarters is an expression of pure ego.

So when compared to other companies which do put out products with similar materials the difference is that Apple never reaches low. They won't sacrifice their premium material usage and expression to reach lower end markets.

Air Pods Max might be the situation backfiring on them. They were so wrapped up in having aluminum enclosures for the headphones they ended up with an overweight and overpriced to many product. It is going to be real curious what a lower cost version of these entail; the rumor is they will come but when and of what materials?