Apple has 10% of computer users??

Naysayers have been calling for Apple's demise for years. But Apple not only has survived but thrived, it seems, at least partially by the sheer force of Jobs' will and his ability to maintain the ferocious loyalty of Apple's users, who still account for 10% of the world's computer users, while its sales usually account for about 3% to 5% of the world global PC market. [Forbes]

Is this true? And how could it be? Here's what one article says:

Macs last longer than Windows PCs. If Mac users replace their Mac every 4 years and PC users replace their every 1.5 years, what does that do to quarterly market share numbers? Not to mention, what does that do to landfills? The important number to analysts, marketeers, software developers, and others should be how many people out of 100 use a Mac? The answer is closer to 10 people out of 100 or 10 percent. Not 3 percent. We get tired of having to point this put, but we'll never stop doing so until the "3 percent myth" is destroyed. [MacDailyNews]