Differencing between 'Need' and 'Want'

This has to be one of the things that pisses me off the most. What is it about the current generation that makes them incapable of knowing the different between a need and a want? Sure, I jest about how I 'need' something sometimes, but I don't do it all the time. Seriously...

Need - Water, warmth and to a lesser extent food.
Want - Something you'd like to have. But you won't suffer or die without it.

Take into consideration the above. Now tell me why people insist how they 'Need' a certain thing. It happens everywhere, in social circles, economy, shopping, even online games. People insisting how they 'need' something like that new brand name shirt. You don't need it, you want it. You won't die without it. Now don't get me started on how the latest expensive brand name thing is a MUST HAVE. That's a whole other debate right there.

Face it, you don't 'need' everything you see. If it really was a need, a lot of people would be dropping dead every time they see something new that they can't obtain. Yet... This isn't happening, is it?