What hobbies do you practice that is other people's professions?

So many
Homelab
Buy broken electronics, repair, resell (so like microsoldering, diagnosing, etc)
Woodworking but I’m bad at it
Cooking
Music but I’m bad at it
3d printing/cad but I’m bad at cad
Language study 日本語
Pcb design and some coding related to this but I’m bad at it
It’s why I get the anti work people. If I could change careers every few years I would. I love learning about new stuff. I post a lot but most of the time I do that is either when I have idle time at work, before or right after work (although sometimes it leaks into weekends). I hate the phrase jack of all trades master of none, it’s cool to know about a lot of things (as long as you recognize the limitations of your knowledge)
- it doesn't matter whether you're good at it or bad at it. As long as you enjoy what you do, that's all that matters :)

Car audio
Auto repair

Gardening or more specifically raising fruit trees. Right now I got about 50 citrus trees growing from trifoliate orange seeds. Once they're ready I am going to graft lemons and satsumas onto them. I'm not planning to sell the trees, rather I'll gift them to friends and family.
I also propagate houseplants and gift them to friends, family and colleagues. Since they're so easy to propagate it's almost no effort.

I enjoy learning vfx through houdini, id be doing it still if it wasnt so annoying to get on linux (im not paying for it, that 260$ a year cost is for me ppl making money and id do it if I was)
Blender is hella fun, like the ultimate sandbox game, cities skylines with no constraints (except much harder) I think with more and more addons it'll be the perfect sandbox creative city builder. Like procedural roads, cities, procedural terrain, buildings, etc. When the laxk of freedom in those games dissapoint you just make animations, the end goal in some of these games like planet coaster is to have something cool to look at and modify freely, the economy means nothing, might as well make it in blender.

I have a bunch of hobbies but the two that I'm currently concentrating on are building guitars and working on motorcycles.
There are plenty of people who build or customize guitars for a living. I have sold exactly one that I built from scratch and that was probably 15 years ago.
I'm resurrecting a barn find motorcycle that I'll sell (or I'll sell one of mine to keep this, I haven't decided), but I'm not going to make any money on it because it's not sought after. I'm doing it for love. I'll break even.

I brew alcohol and grow mushrooms(gourmet and non-gourmet)

I write software for fun and give it away. I also write software for money and don't give it away.
- Good man!
- 🤘 Ditto!

Not exactly the same but Truck driving Simulation on PC.

I bake fancy sourdough, grow vegetables, do landscaping (but not mowing) make great cocktails for people, ferment foods and drinks. Occasionally draw things for decorations.
On the other hand, we pay someone to mow, and also to clean the house every other week.
- I tried my hand at sourdough breads, but failed miserably. How long did it take you to become decent at it?

Photography. I got back into it last year and have really enjoyed the process. I’ve learned a lot in a really short time.

Gaming.

I do almost the same thing as a(n unpaid) hobby that I do as my (paid) job. I'm a software developer who writes open-source software on the side.
I've also seen a few of my other hobbies grow into serious industries with real employees. The (hobby) drone industry and the 3D printing industry are quite large and growing (I assume).

Linux Sysadmin here.
I have a couple open source apps/scripts that have tens of stars and ones of forks. I'm also getting into micro soldering to fix electronics. Mostly for myself but I'll hardmod or fix friends equipment for cost of parts. I've been known to buy a broken console, fix it, mod it, then sell it for some extra cash to buy more soldering equipment.
- Nice! What are your projects?

I have a machine shop that I use for making things out of metal that are normally not made of metal (like a yarn winder).

According to my ex, I'm pretty good at defending the horrible actions of others in a conversation
- You have a future in politics!

Apparently I study timekeeping so much that I can program a clock on a graphing calculator without using any timer function.
It takes a fixed amount of time to alter a pixel on the screen, and when carefully crafted, the pixel clock itself serves as a timer.
I'm actually currently testing such a clock demo on my Casio right now.
- are there significant differences in pixel response as battery voltage goes down?
  
  Welp, one of my 4 batteries died today (no worries on the memory on this model). I found a spare battery, but between that and switching back and forth to USB power, it does seem the calculator's speed might be lightly affected by voltage levels and even possibly by temperature.
  Hey, ain't nothing perfect...
  
  Very good question!
  At this moment I don't know for sure.
  I've only been running it on consistent 5V USB power until yesterday.
  I am keeping the voltage level question in mind though...
- Timekeeping?
  
  Yes, as in the studies of everything between keeping up with time zone rules, knowing when the next lunar eclipse is (in the USA that's coming up shortly early morning March 14), and even learning and understanding how long different CPU instructions take.

Apparently there are people who receive monetary compensation for drawing comics. Some apparently can even do that as their main job. That's what I heard at least, they seem to be rare.

I play golf, some days I wouldn't even call it a hobby more like penance and a walk in the trees and sticks

Welding! Just personal projects

I fix my own cars and do my own house maintenance.

I got really into cocktails a few years ago (or "mixed drinks", if you want to be more technically correct). No way I'd be able to keep up at a real bar, even if I probably know more cocktails than many of the bartenders I've personally interacted with (TBF I haven't been to a bar since I really got into cocktails, and before I got into it I just went wherever it was cheap). Fixing drinks is at best half of the job anyway, and I'm rubbish at the people stuff.
- What's the distinction between cocktails and mixed drinks?
  
  "Cocktail" is more specific. Originally, it was identical with what's now called an Old Fashioned, i.e. spirit, sugar, bitters and water/ice. Later the term started including other alcoholic drinks like sours, martini etc.; I've seen people claim in discussions that's it's down to the amount of ingredients (e.g. a Rum & Coke is not a cocktail, but rum, cola and lime (Cuba Libre) might be) or a specific care exercized in preparation, but I think it's ultimately arbitrary.
  Anyway, one of my favourite drinks is the Twice Up (whisky and water mixed 1:1, works great with many other spirits). Hard to call this a cocktail, considering adding water to whisky is just a completely normal way of drinking whisky in Scotland. The Scots just pour the water freehand instead of measuring an exact amount.
  
  One was mixed with a cock, and the other was mixed with a tail, obviously.. /s

I'm trying to get into creating electronic circuits. I'm terrible at it, though.
- If youre doing soldering flux will change your lifeq

I try playing the guitar and taking photos.

Kind of the opposite, but I void warranties for a living. Pays pretty well too.

I make and publish music but not popular enough to live off of it.

My current favorite outside of gaming is selfhosting or homelabbing. Maybe not to a high degree but I manage four local servers and one offsite, with four websites. It’s pretty fun but makes me super stress when it fails. One of those websites is a work related database but it’s also very fun to manage.
Another small hobby I have is managing my own small library. Using LOC codes I learned from the library. I inherited a massive collection from retiring profs.

cycling and drumming (in a band), not easy to find the time with all the other stuff (chores etc.) that has to be done