But then, they lose interests (and endorsements) of software engineers and IT professionals. And, in the words of Steve Ballmer "developers developers developers".
If they want to sell hardware, they need to convince me to recommend them to the person who asks my advice. (rhetorical "me")
"developer work on an iPhone" . Sorry, I don't get it.
> I really don't understand why they fail so hard to update their hardware.
It's not because of their monopoly-like status, it's because they make so little money on Macs compared to the vast sums of money they make on iPhones. They probably look at their developers, and ask "how much is it worth to us to have this developer work on a Mac? How much is it worth to us to have this developer work on an iPhone?" and the iPhone wins out every time.
Which... well, sucks, for the rest of us, but it's not laziness—it's opportunity costs.