The open source hackers I know are motivated largely by perfectionism, a feeling that a world in which the best possible software is not available free is just, I don’t know, inelegant.

It’s not an altruistic desire to alleviate the suffering of particular people, in fact most open source projects, especially early ones, seem to be incredibly ineffective to this end. If Linus wanted to help staving children in Africa, Linux seems like a poor choice for his energies. One-laptop-per-child is a notable exception. It could well be argued that Bill Gates has been far more effectively altruistic in his support of health in the developing world than any open source author.

It’s my understanding that the motivation for Linux was far more academic. The thing Linus didn’t like about Windows wasn’t that it was harming people financially, it was that bugs in Windows (of which there are plenty) couldn’t be fixed efficiently by the computer science community. His goal with Linux, as I understand it, and I think this is true of many open source hackers, was to produce an OS that would achieve a higher standard of quality. He chose the non-proprietary route because it works the same way as the academic world in general, academics the world over are free to build on any previous work in their field. This is obviously the most efficient and elegant way to make new math, and mathematicians (of which hackers are a subset) hate inelegance and inefficiency. If they didn’t, they’d be social scientists

In short, I’d say aesthetic concerns like “perfectionism” or “elegance” are the primary non-standard-economic motivations of the open-source community.