Ask HN: What are the patterns of self-employment? 10 years ago
"that sort" is actually quite clear for me. I am rather curious what do you mean by "the patterns"? :)
I personally own a small SaaS product. I've started it as a side project being an employee, and eventually developed it to the point when it substituted my daily income.
Am I passionate about that particular SaaS? I am not sure. There is a good advice (I've heard it from Dane Maxwell I guess) — you have to make serving other people your passion. Or solving other people's pains.
This way you'll always have passion in what you're doing, regardless of its "shape" or a product form.