I grew up in the 70's and 80's and back then if you had torn jeans you were too poor for a new pair or your mother couldn't sew. I noticed a trend around the 90's of young people wearing torn jeans but I never seem to see any of those now middle age people stepping out with this look just young people still. Is it around the time you realize your heroes wearing the same stuff are actually just stupid bums or is it something deeper?
Most clothing fads I've noticed either go away on their own, or get dropped in year 3 or 4 of Uni, when looking good for a career path seems like a better choice than looking good for your buds.