No, it's because I've used the other alternatives and made a rational decision. I tried Ubuntu, it didn't work with the hardware in my laptop, the trackpad was useless and it didn't run a number of programs I require (the Creative Suite, for one). I would happily use Windows, but the hardware Apple creates (in my case, the Air) is largely unparalleled in terms of build quality and weight. So, OSX it is.

These are all measurable, quantifiable things. While I can't disagree that marketing affects people, to suggest that the reason everyone likes something is because of conditioning is a gross generalisation.