ASD: Self-diagnosis at age 26 sparked initial interest, assessment and professional diagnosis at age 33 intensified it. Every book, every documentary, every YouTube video, every blog, every forum... This seems to be a common interest among WrongPlanet users.
Photoshop: I have been told that I use my camera to distance myself from other people and/or my surroundings. Photography is a coping mechanism of sorts -- I have been known to return home from being out-and-about with several hundred photos. (Long before Instagram was a thing!) The more social expectations and sensory input, the more photos. I can spend hours upon hours -- losing track of time, forgetting to eat, refusing to sleep, etc. -- labelling, categorizing, and editing digital photos, most of which I am the only person to ever see. I have tens of thousands.
Autobiographical Introspective Writing: As above, my primary literary audience is myself. I can simultaneously lose myself and find myself in my writing. I have more than 6,000 [locked] blog posts.
Thrifting: I visit thrift stores somewhat obsessively, typically without a purchase goal. I am so familiar with one thrift chain that when I am in one of the stores and I notice an item out of place, I divert my focus from treasure-finding to organizing items throughout the store (ensuring clothing is hung in the correct section, reuniting separated multi-item sets, ordering series books chronologically, collecting like-items and placing them together on shelves...).
1970's Television Sitcoms: Especially the Mary Tyler Moore Show. This was more of an intense interest as an older child and teenager (in the 1990's), waning in my 20's (in the early 2000's), but I still have boxes of VHS tapes and DVDs, the actors' autobiographies and biographies, old TV Guides purchased on eBay, and so on. Although I no longer watch the show every day, I cannot imagine parting with my long-ago collection. And truth be told, I still light-up whenever someone happens to mention one of 'my' shows, sitcoms that went off the air a decade or more before I was even born, and I have been known to happily rattle off (unsolicited?) information and trivia.