Apple's lack of market share is due to how Apple is branded. Part of telling people "how to buy" is part of the Apple brand and culture.
Alas when it comes to market share, there is nothing inherent in Apple's branding that appeals to normal mainstream people.
-- Most people don't sip caffe latte with the Dalai Lama or daydream about the works of famous creatives.
-- Most people don't live on trust funds and spend all day making DVD's and playlists for their iPods.
-- Most people don't collect art and do not need their computer to look like a mushroom.
-- Most people are not involved in some sort of counter-culture dissent movement.
Apple is a cult. Their lack of market share is not a bug, it is a feature. Apple's brand does not support massive scaling of the customer base -- because the additional cult-compatible customers simply don't exist.
By Apple's own count, there are 7 million OS X users. That's a number, that as percentage of total personal computers in use, is very close to either 0% or 1% of the market. It's the fringe.
And Apple, to their credit, is somehow managing to survive out there. Somehow reminds me of a bunch of rag-tag hipsters and artistes "fleeing the tyranny of the Cylon empire". God bless them.