[smeej]

Even so, it's not the only alternative is gigantic companies trying to get everyone using their product.

If every plumber in your area had a subscription to your software that was specifically tailored to your codes and the nuances of your area? Estimating costs based on actual local prices for things? Could you support the number of people it would take to keep such a thing running? Could you sell insights from the data to the local hardware store to help them figure out what kinds of changes (weather, construction, whatever) lead to what kinds of demand for products?

It doesn't have to be "you could walk to it" local, but if you really created the tool your area's local businesses couldn't live without, could you really not support yourself?

[harimau777]

A lot of people prioritize working on software that intellectually stimulating. If someone is an expert in medical simulation, sonar, VLSI, etc. I don't think that they would consider developing plumbing software to be an equivalent job.

[smeej]

If they're an expert in medical simulation or sonar, aren't they likely already working for a relatively small company, and one that's located near, say, a hospital center like Boston, or an ocean? That's still a service within their locale and to their local community, even if the local community is also engaged in specialty work that benefits the whole world.