I like learning about random ass hobbies without ever indulging in them.

I write sci-fi/fantasy stuff, and I do this too, but mostly so I can gift this or that character with some plausible insider info on a hobby THEY have.

The trick with creating a fantasy/sci-fi universe is to sprinkle true/plausible things all around the little details, so the obviously fantastical that doesn't have grounding in reality will be accepted by the reader.