When you're a long time user, you know how to do everything with what you're using - whether that's an operating system, a programming language, or something else.
The latest product isn't good and your suggestion is "don't buy it." OK, what do I do instead? Buy a Windows or Linux laptop where I have to re-learn a decade's worth of knowing-how-everything-works? Build up my natural flow in a new OS? Find whatever are the Windows alternatives for all the little things that I do on my Mac?
I'm not saying that companies owe things to their customers, but I think it's really simplistic to say that it's just an emotional investment and misplaced loyalty. People have a tool and then a company makes that tool worse. There are other tools, but it takes time to learn them, figure out their differences and how to get everything done with them, etc. Pretending that there's zero cost to switching is disingenuous.
For example: if you're a software engineer and someone made your main programming language bad, there's a high cost to switching to a new language. Even if you're excellent at learning new languages, you don't know which libraries are good, you don't know what various functions are named, you don't know what warts are in the build system (and how to avoid them), etc.
It's not just some emotional response or misplaced loyalty. It's that you've built up skills over many years that are tied to that thing.