In my view, if you're going to do a business on your own, you have to be focused. Between the other parts of life that need some attention, the care-and-feeding of the business, sales, marketing, and promotion, there isn't that much time left for actual development. So, you need to pare down your problem space/feature set to the absolute minimum that provides real value to people. This sounds like what you're doing with your "consulting only, no development" approach to most clients.

In my case, the project I just finished prototyping (yes, this is a plug/request for feedback, although the product is of extremely limited interest to this community) solves a narrow problem in the electricity industry: Energy meter data is passed around in an obscure binary file format (MDEF) that few people can understand, read, or troubleshoot when they receive a broken file from a 3rd party. There's a need for a tool to wrangle this format, and I believe I can do one that's better and cheaper than anything out there, with a modest effort.

As for why I'm a solopreneur: I didn't know any good co-founder candidates, and didn't have a compelling sales pitch. ("Hey - let's quit our jobs, and poke around for a product that we can try to build into a successful business" is a little too honest!) I also didn't want any more of my life to drain away writing vbScript (long, long, long story) and, as the great Peter Gibbons put it: "I don't think I'd like another job".

I'm not philosophically opposed to growing the company, but it will have to be from a "given this problem, I need more people" angle, rather than a "let's enlarge the team, and hope something good happens" view.

P.S. http://www.mlsite.net/meterdoc