A huge failing of our society is that we don't teach people how to be responsible with money. All they see are ads telling them to buy more, spend all your money, keep up with the Joneses.
Either you have parents who teach you, or you figure it out on your own. And for the poorer people, it's just a cycle where they don't know, so their kids don't know.
I myself didn't realize until I stumbled upon Mr. Money Mustache two years ago (http://www.mrmoneymustache.com/), and it kind of woke me up. Now I buy way less, save at least half my income every month, and am overall much happier.