I think there's a distinction between "apps" and "tools"; I doubt anyone would spend years of their life and thousands of dollars in UI testing trying to make,

I think there's a distinction between "apps" and "tools"; I doubt anyone would spend years of their life and thousands of dollars in UI testing trying to make, say, an accounting package, and then give it away. On the other hand, many people write useful tools — even business-critical things like rsync and ssh — and give them away freely. As somebody who has contributed to a few open-source projects, and even put up some code of his own (that nobody else is ever likely to look at or use - but at least it's out there), the main reason I do it is because I like to master skills and concepts - the code is just a reside, a side-effect that proves to other people that I've understood the topic at hand. It makes much more sense to advertise my skills to as many people as possible than to try and make people pay to see how good I am. A second reason is that nobody should ever have to re-solve a problem with known solution (unless they really want to). When I can see somebody struggling with a problem I know how to solve, keeping the answer to myself, or (worse!) extorting the other person is jerkish behaviour; I hate when it's done to me and I won't do it to others. Finally, actually making a product and selling it involves a whole bunch of skills and responsibilities that are largely alien - sales, market research, management, etc. I could go out and learn all those things, but that's time I'd much rather spend on helping people out, and becoming a better programmer.