Certainly, but you're also a product of an environment which values that sort of self-expression. If every time you went and hung out with your friends they shamed you, saying you look homeless, you might think differently. Its certainly a sign of maturity to not really care about those things, but depending on your life trajectory different values will hit. And clearly, a lot of people value a new iphone.

OTOH - its a device that you use for hours and hours a day, for entertainment, organization, communication, and a camera. Having a "better" one is a decent investment if it helps all those areas.