It's not only the students who show off their new phones, working people do the same. They have different reasons in doing that but you're right, some do it just to show that they're rich and can afford a very expensive and the latest cellphone.
I don't know if it's to show off you're rich, you can get the best smart phones on the market for a couple to a few hundred dollars if you sign up with a 2 year contract.
