[rbanffy]

> How does that even makes sense?

That's not a really useful way to argue. See http://www.paulgraham.com/disagree.html

Your open-source heart rate monitor will arguably directly help more people than the proprietary ones (don't confuse open-source with gratis) because it can serve as a base for other solutions to different problems. What you actually did by developing your open-source equivalent was to employ your resources in a much more efficient way, distributing its returns across a much wider field.

It's true you hurt the very limited group of people who made proprietary monitors, but you benefited a much, much larger group much more than they could ever do.