I think a bit of every group is in the mac demographic.
I'm in the working-middle class I suppose and 28. I'm a self-employed tradesman and I have to work hard for my money, sometimes I have good month, sometimes I have a bad month. I have to save to buy the things that I want (like my new macbook air). I can't just go out and buy a new laptop on a whim. But on the flip side If you have to work hard for things you appreciate them more.
I even made my own sleeve for it because I couldn't justify paying £30 for what is essentially a big thick sock, I just went to the local textile shop and bought some thick wooly fabric for the outside, velvety material for the inside and some padding for between the 2 layers all for about £5 and spent an hour or so sewing it all together.