I believe I've heard this once put thusly: "If you make your avocation your vocation, you'll get no vacation."

Depends on a lot of things. I started an apprenticeship machining, and now I want to turn my garage into a machine shop.

I think the important thing is that you make sure you keep some of it for you.

If I did turn my garage into a machine shop, it would be tempting to start taking orders. That's where my hobby would turn into more work, having to meet orders and timelines.

you are mistaking having a hobby with having a true passion for something.

the problem is that a lot of people are passionate about nothing.

I work with programming, and I used to think this was the case. The reality is that I just do it even more as a hobby as well.

So true.