Ask HN: Should I Open-Source my Startup?

I've noticed I'm more motivated and effective as a developer when working on Open-Source projects and can share what I do with others. However, the project is going to be monetized through getting % of deals. So, I'm a little bit afraid of competitors who could use my code base to offer cheaper or even free service. Is the fear is justified?

P.S.: I've tried an approach of Open-Sourcing separate components. It increases the whole quality and maintainability. But it takes much more time to create everything in a universal enough to be reused form, to elaborate documentation for every independent component, etc.