Interests don't always have to be about collecting - I'm absolutely obsessed with "Doctor Who" but apart from the actual DVDs and books, I just have a single action figure!
People who collect a ridiculous amount of stuff are more likely to show their collections off on the internet, so I think that skews our ideas of fandom a bit. And I'm not convinced the people with massive collections actually enjoy them more than people with, like, a sensible amount of stuff.
I live independently and can work, but only in a low-paid job. I have some interests that could possibly be turned into manic collecting. I can't afford to, and I don't think I even want to.
Lego: many YouTubers have basement Lego rooms the size of my entire home, filled with vast dioramas and literally millions of Lego pieces. My Lego fits in 6 shoeboxes. That's fine. I still love building with it.
I've collected maybe 25-30 Transformers toys over the past 2 decades. There are people on the Transformers forum who buy that many in 2 months, but I'm pretty damn sure I've got 100 times more joy out of each individual toy than they have. They often go online to whine about the poor quality of a toy they "had" to buy for their collection.
Guitars: richer men of my age and up go a bit crazy and buy themselves 2 dozen fancy guitars at £700 - £25,000
each, which they may or may not be able to play more than 4 chords on. One of my uncles is a prize specimen of this. I have one (1) guitar. It was cheap, secondhand, and has a dent in the soundboard. I love it and have played it every week since 2005.
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You're so vain
I bet you think this sig is about you