It's a Mac app, pricing model is perpetual license with paid upgrades for major new versions (every 3-5 years). Customers are roughly 50% individual devs and 50% companies who buy for their employees, and a bunch of educational licenses, but I don't earn much from them.

I got initial traction by being mentioned by some popular bloggers and twitterers, but I only started making a full time income after two or three years. I think marketing is mostly word of mouth, and lots of people using the trial version who eventually buy a license, but for the most part I have no idea how people find my app.

As for whether it's worth it -- it's a cushy job, I can take care of my kids and don't need to worry about putting in enough hours, because nobody cares how much I work.

On the other hand it does get somewhat boring after 10 years. I've been hearing the same feature requests and ideas for improvements for 10 years. My customers are all the same average tech dudes like myself. Sometimes an interesting bug shows up, and when I track it down that's the highlight of my week.