I think a trend begins with a certain style. It can range from a celebrity wearing something a certain way, to an average Joe or Jill who notoriously wears something that becomes fashionable or fun. It continues with others wanting to sport that same look. And when it seems like multiple people are sporting a specific style... you got a trend.
The key in fashion is inspiration. Without inspiration, you're basically just throwing together clothes. Inspiration may even come along with pieces inspired by celebrities, musicians, athletes, etc. I am even reminded in the late 1990s of message T-shirts saying stuff like "I Have the Golden Ticket" and "Dump Him." But I think for it to become a trend, you have to see lots of people sporting one style or wearing a certain style in different ways. Like when lots of people wore skulls (you know how I feel about this, so I won't waste your precious time), it was because someone got looks to sell, and it caught on with people. Do you have to follow trends? Absolutely not. But if there is a style you love, I'm sure you'll want to sport someone else's look and style with your own personal flair.
The thread is about GENUINE trends, and sometimes, genuine doesn't always mean following design cues from designers and stylists. It can be from average people who probably aren't even trying to look stylish or cool. As the name of an old movie suggests, "Gold is Where You Find It."