I was doing some contract work on the side while building the MVP, but switched to full-time right after launching it. I wouldn't necessarily recommend that though.. basically burnt through all my savings over 4 months. Right as I was starting too look for more contract work I ended up winning a $15k grant from YC [0] which bridged the gap until I got to profitability. Now at around $6k - $10k/m (not recurring, so it varies).
There's also a sort of survivor bias to it. If he were willing to cash in, then he wouldn't have a $10,000,000 collection and they wouldn't be writing a story on him
Full time job, and 1 - 2 side projects that never really get finished. My goal is to make something I can eventually turn into my own business, but I found my self encountering two main pieces of conflict: 1. None of the ideas are ever really good enough or directed enough towards a specific niche to be successful, and 2. I find I am usually happier when make myself take breaks instead of working on projects on the evenings and weekends, but I'm not sure how I can eventually have my own business if I don't.
When you started your business did you have another job and build your own business on the side? Or were you able to jump straight in?