Development costs of open source software
Developing code takes time, and therefore its costs can always be measured, at least, as opportunity costs. Without focusing on code ( open source or not) financed by companies, the costs of development are normally absorbed by individuals. It may start as a simple plugin for a larger platform, a cool command line tool. This is a short snippet from cURL history (released for the first time in 1997):
Today, I am employed by my forth company during curl’s life time: Mozilla . All through this project’s lifetime, I’ve kept my work situation separate and I believe I haven’t allowed it to disturb our project too much. Mozilla is however the first one that actually allows me to spend a part of my time on curl and still get paid for it!
However, developing open-source code can have an intrinsic value for the creator(s) since it becomes a way of making a name for themselves. In the same way that you can grow your online persona with smart performative blogging , you can achieve something similar through releasing code, whatever you feel more comfortable doing, sometimes even both.
I also believe there is also another possibility, which relates to the joy of contributing. If I can make a tool perform better, or provide some value to a group of people, then why not just go ahead and do it. The biggest difference with other products, is that software has a virtually zero marginal cost for the developer, which makes it easy to scale. On the other hand, Maintenance costs of open source projects are often undervalued.