I started the business because I've always loved writing, am good at navigating tricky job search and career situations (I've seen it all after 20 yrs in recruiting), and I enjoy it more than recruiting. I also noticed most resume writers didn't really have a background in hiring, but rather were just trained writers that probably had a hard time making it in journalism or other areas.
I'd been writing resumes for my recruiting candidates for many years, and many of those candidates would rely on me for career advice as well. It was odd to provide career advice as a third-party recruiter, as there were times when I might have some financial interest in what a person does. As an example, if someone approached me and said "Should I leave my job?", a recruiter might say "yes" with the thought that if this person leaves I might get a placement fee if I help them find work.
Resume Raiders is now my primary focus and has been quite profitable since it started. There is very little overhead. I live in a pretty expensive area, but my clients come from all over the world. I also offer a discount to HN'ers (see my profile page).