There are a few different answers.
Well, Macs do not cater to a DIY crowd in terms of hardware. But how many people want to go through the effort of bulding their own PC, upgrading it, etc.? Macs cater to those who don't want the hassle, not just in terms of hardware but in terms of software, the OS, the apps, etc. too. While you can do a lot more with the OS and software if you want (CLI, X11, *nix, whatnot), the user experience is designed for those who don't and shouldn't have to do a lot of upkeep, those who don't want to learn new ways of doing things all the time, people who find advantage in working with more tailored tools for a given job, and using many such tools together on a work rather than being boxed in by an app or a software suite. The idea ultimately is that you spend less time on sharpening your tools and more time using them. Macs sacrifice some (not as much as people may think) flexibility for more predictability.
So, in summary, a Mac is for the lazy people, like me. Here's to the lazy ones...
