That Apple serves as a "Veblen goods" lifestyle brand is well established. Your amusement is what's weird.
Of course people show off their iPhone. It's a big reason of owing one, it's also a big reason behind slight/major redesigns (people are able to show they have the latest model).
Perhaps you take "show off" literally, like someone going "hey, look, I have an expensive phone"?
It's way more subtle than that, only someone totally crash would do it that way. It's done the same way people buy expensive sneakers and clothes, or how people buy Teslas (or used to) and similar stuff. As a consumer identity that signals you afford a higher cost lifestyle.