Cereal Box Collecting
I've always loved breakfast cereal. I was a kid in the 80's and 90's, I considered collecting cereal boxes. I saved a few here and there over the years, but it never really got to the level of being a collection. This dude came to the same crossroads and took the other path, and he now has a museum in his basement with over 8,000 boxes.
On a side note, if any company could ever get the rights to use all of the trademarks, cereal boxes would make a pretty awesome trading card series. The front and back of the cards could be exact replicas of the cereal boxes themselves, so you could have different versions of the same cereal depending on the year it was released or the prize inside.
Video source: Perfect Duluth Day