No, not the Marvel character, The Collector, but we mere mortal collectors of things. Bu just as with any good comic book hero/villain, every collector has their own origin story, of how they first got into collecting and why they collect the things they do.
My first collection was a magazine series about dinosaurs when I was a kid, maybe 5 or 6 years old. Like every child around that age, I was fascinated by dinosaurs. Jurassic Park was playing in cinemas and all the associated toys and merchandise advertising on TV, it was a great time to be alive, as a dinosaur fanatic. My grandparents signed me (themselves) up for a one of those fortnightly/monthly magazine subscriptions. Along with a magazine full of articles, dinosaur facts and trivia and a red/green 3D image in the centerfold. I had to Google it, it was just called Dinosaurs! Magazine by Orbis Play and Learn.
Each issue came with a silver collectable card booster, with trading cards for what felt like every dinosaur that ever existed, for a 5-year-old. Each card had artwork depicting a dinosaur in its natural environment, or the artist's interpretation thereof, and a brief description of the dinosaur on the back, and a number indicating that there were more cards to collect!
To cap it off, each edition came with a single piece of "skeleton" that issue by issue, eventually lead you to building your very own glow-in-the-dark T-Rex skeleton! I mean what kid wouldn't be hooked.
I think there were over 100 issues made with over 300 dinosaur cards to collect and trade. The magazine went out of print long before I lost interest. I believe this to be my origin story, as it was from around that time, where I would consider when I developed my enjoyment for collecting, in particular that drive to collect and complete a whole set.
Thanks for staying a while and listening.