Because that’s what the market cap suggests:
But not the book value:
The data suggests that relative to other tech companies AAPL is significantly overvalued. And going forward there is no guarantee that AAPL can justify today’s value by keeping up its dominance of the sector. Tech is an extremely fickle and fast-changing sector where one year’s turkey can be next year’s prize pig. And AAPL’s product lineup is still dominated by products developed under the charge of Steve Jobs — it will take a while longer to fully assess whether or not AAPL can succeed at the same magnitude over the entire product cycle from conception to sales without his leadership.