I'll refer you to the dictionary definition of a monopoly :-)
On the tech side, Apple lappers are so much better assembled and designed than PC ones it's not funny. And the support is superb. These things matter if the box is what you're depending on for your daily bread.
And if you think Microsoft has any shame at all, then you're more charmingly naive than I thought. Of course, Apple does have the advantage that their software is mostly good and occasionally sucky, whereas our dear friends in Redmond are at the far opposite extreme of that continuum.