Much of what has made Apple successful is the idea of what a Mac, an iPod, or an iPhone is. For most of the iPod's lifespan it was not the best product on the market, it was just the best marketed. In the case of macbooks, the hardware has been roughly on par with equivalently priced competitors for several years. But they sell the idea of what it means to be a 'mac person'. They get you invested in the idea that macs are better regardless of the reality.
And that strategy is as much about reassuring people who already own Apple products (fighting buyers remorse, and grass-is-greener impulses) as it is about selling more.