It's mostly based on design: good UI design and good aesthetic design. Apple is almost a fashion company.
It's not based on any of the things that the windup MBA idiots always harp on: marketing, performance, salesmanship, connections, etc.
Sure, Apple has those things. Apple is great at marketing, their stuff performs well, and they have plenty of salesmen. But so does everyone else. Apple's success is based primarily on aesthetics and user experience, which nearly all players in the industry have ignored completely in favor of the cliches beloved of MBAs.