Because the tools to write OSS are cheap. A laptop and a brain are enough. Everybody already got them. About time and paying one own bills: some people voluntee

Because the tools to write OSS are cheap. A laptop and a brain are enough. Everybody already got them. About time and paying one own bills: some people volunteer and somebody are paid by their employees to write open source or to occasionally contribute to it. I did it myself years ago. We needed to add some functionality to an OSS library and I asked to my customer if I could send the patch to the project on GitHub. They told me yes and I believe it's still there. GitHub inflicted 2FA to me for that later on, but that's another story. Some scientific research tools are as cheap as what we use to write software. Other tools cost a lot, from the 10 thousands to the billions. They are funded in several ways from universities, research labs to transnational entities. That could change with AI models because collecting data and training cost a lot, but they are not the usual OSS piece of code so I'm not sure that they belong to this thread.