I think there are two general types who succeed as entrepreneurs--one type enjoys starting businesses, any business. They tend to be good at general business operation and management, and are often serial entrepreneurs, who start up, build, and then sell off a number of different business ventures. For these folks, it doesn't matter so much what the business actually is, they're just good at starting and growing businesses generally.
The second type (and this is the category that I fall into) is someone who recognizes a certain aptitude and skill set within themselves and builds a business around this. My business, helping employers identify and recover Workers Compensation insurance premium overcharges, grew out of my experience in the commercial insurance field, yet this niche business is quite unique and distinct from traditional roles in the insurance field.
While working as an insurance broker, I found that I could help clients recover Workers' Comp overcharges--and that I enjoyed that sort of work much more than I did the more traditional role of insurance broker. Additionally, I very much liked the idea of working for myself (avoiding the kinds of office politics and bureaucratic decision-making I had seen while working for larger organizations). I also had some unique skills and experiences that seemed to be useful to someone who was going to be running the whole (albeit small) show. I enjoyed being involved in the entire business of promoting, marketing, and developing a small business (as long as it was my own small business) and I have found that doing this calls upon lots of different kinds of skills, from developing sales materials to web site development and search engine optimization (all the while also doing the actual technical insurance work that is the basis for the company's existence.)
The key to this business, for me, has been that it suits me psychologically. I enjoy the work for it's own sake, and yet I can also make a decent living at it (although it has had its ups and downs over the years, as many small businesses have.)
It's been an extended post-graduate course in business (even though I never studied business in college) and it has utilized a number of skills that I was, fortunately, fairly good at. My work requires strong communications skills, both written and verbal, as well as an ability to dissect and analyze somewhat technical material. But in addition to that, running and growing a small consulting practice for over 20 years has also meant I had to learn how market, network, and promote the business.
Fortunately for me, I was good enough at those things to make a go of this. I now even have a second generation working with me in the business, as my son joined me a little over six years ago.
I've also been fortunate in being able to team up with some talented and smart people who work with us as independent contractors. They enable us to function as a somewhat larger company than we are on paper, because these long term "partners" have brought additional skills and insights to our operation (but because they are independent contractors, paid on commission, we've been able to keep our fixed costs low.)
I wouldn't be good as one of those "serial entrepreneurs", I don't think, as I don't think my particular psyche could grow a business I wasn't passionate about personally--and I couldn't bear to sell it off to strangers. But as a "Type II" entrepreneur, one who enjoys having his own small show to run, it's worked out pretty well for me (so far, at least). After doing this for the past 22 years though, I've also learned that it's difficult to predict what the future holds. How does the old saying go--"Man plans, God laughs".