What people here seem to be missing is that it isn't only that "have-not" kids envy the "have" kids. It's also that there are "have" kids who take great pleasure in rubbing the other kids' noses in the fact that they can't have nice things (or at least not as nice as the Rich Kids).It's not about making kids unhappy, it's about people being forced to change how they live their lives for no other reason than to spare the feelings of others. If a kid is seriously feeling anxiety over what clothes their peers have (as the article in the OP claims), then that kid's parents have failed him/her. They failed their kid by not teaching them to be happy with what they have and not to worry about having all the fancy things in life.
I wasn't one of those kids who coveted my classmates' fancy things. I actually was mostly fine with what I had*, and if my classmates sneered at some of the second-hand clothes or home-made clothes I wore to school, that said much more about them than about me. It's what was affordable back then.
*After enduring three years of hell in junior high over clothes, I asked my grandmother for some blue jeans to wear when I started high school. I was not prepared to put up with three more years of bullying and ostracism for such a stupid reason.
My first year of college was the last year that I ever wore jeans. I noticed that the unwritten dress code seemed to be more relaxed, as students and instructors wore whatever they wanted. So I went back to my previous style of dress and have been comfortable ever since. And if anyone objects, they have my permission not to look.