Because I prefer the intuitive software, the reliability (".....has encountered an error and needs to close" doesn't occur on my iMac. Ever), the design/aesthetics and most of all, the effortless integration between my other Apple consumer products (iPhone, Apple TV, iPad etc). Yes it's expensive but then so was my BMW 330ci convertible. Doesn't make it overpriced. It means its quality and is the result of exacting design, research and top quality materials. I have a saying; "cheap price, buy twice". And that is fundamentally what you're getting with WIndows-based machines which are always built by 3rd party manufacturers. Before you ask, yes I also own a windows-based laptop and I hate it. It is unreliable and under spec'd despite my loving OCD-esque maintenance. But I use it because (A) its cheap to replace and (B) because it's cheap its suitable for purpose and I don't mind it becoming dirty or scratched (I work offshore). It would break my heart to see the beautiful exterior of a MacBook getting damaged.
What I believe the root motivation for you 'Apple haters' is the fact you didn't quite do well at school thus resulting in a mundane job which doesn't pay well enough for you to be able to afford and Apple device. For that I feel for you. I however can quite comfortably afford most consumer purchases and if I wanted could build my own PC that could rival NASA's offerings. But the flaw would be it would be running Windows. So instead I opt for something with the positive attributes I have mentioned above. Apple.
If it's not for you then its not for you but don't get on your soap box and proclaim that its not worthy. Obviously the sales figures and the fact most professionals (that don't have a job putting digits into a spreadsheet - think architects, graphic designers...in fact, most design disciplines) use Apple computers.
Stand by for incoming