[rifung]

> It doesn't really cost anything to open source something though.

Yes, it costs next to nothing to just open source a project if you mean literally just putting the source on some hosting site.

However, open sourcing something properly, where you respond to issues, document things properly, and provide build/test infrastructure to external developers is much more work. Not only that but you have to be much more careful when creating APIs and be much more vigilant about keeping backwards compatibility.