I liked the article and the wikipedia page for hobbies is very interesting, I've found some gems...

- Magnet Fishing (https://en.wikipedia.org/wiki/Magnet_fishing)

- Binge watching ( didn't know it can be called as a hobby - https://en.wikipedia.org/wiki/Binge-watching )

- Constructing languages ( https://en.wikipedia.org/wiki/Constructed_language )

- Tea bag collecting ( https://en.wikipedia.org/wiki/Tea_bag )