It's usually user preference, and paying for the OS for most people. Yes I know, some hipsters pay for the shiny logo and use it as a tumblr machine, but thats not true about everyone. I use it because my favorite programs run on it, and I love the way it works. I built my own mac for cheaper and I get killer performance out of it, but if I did have the money and no technical skill I'd gladly pay to get a nice imac or mac pro