I left a job with higher pay to start in a machine shop with crap pay. I like the shop environment and learning about machining. Like yourself I like machining, welding, etc. Before starting in the machine shop, whatever I know was self taught and came from books, Youtube, Google, etc.
I hope to make some money on the side with my own little existing "machine shop" (manual lathe & "Bridgeport" clone, welders, cnc plasma cutter, etc).
However, would I want the stress, risk and responsibility of being a full time job shop, I'm not sure. I've recently had my own excavation business for 17 years and it taught me a lot about customers and business. Don't know if I want to jump in full time business in job shopping. My boss often sleeps at his factory to get the jobs done. Many times he opens the door in the morning with puffy eyes, it's obvious he hasn't had a good 8 or 9 hours sleep.
I know it's easier said than done but I'm always trying to think of things to make and sell. I like the concept of design/make once, sell many times, and improve the manufacturing process. I have a big respect for job shop guys that have to think of a way of making a part every single time. They have to make it fast, good, and on budget. Every time I make something for the first time, it takes design, experimenting, finding parts & materials, blah blah blah. If I had to make it a 2nd time it would be easy, a 3rd time easier still. But job shopping mainly seems to be get it done fast, cheap and correct first time - stressful unless you are really good and it comes easy.
Your passion may fill you full of energy and enthusiam, which may help you through any obstacles, and lead you to success. Hopefully doing your passion as a business won't kill the passion in the process.
Good luck with your direction.