I agree with you rationally, but I do see why people would do otherwise. To an extent I did so myself, and I'm abnormally rational.

I think it's because people see things that they consider 'good causes' (be it open source software or doing medical work in refugee camps in Africa) through rose-colored glasses. I guess that sounds like stating the obvious, but it's not until one does these things for long enough that one is really confronted with the realities and gets a more 'fundamental' understanding of these dynamics than just rationally 'knowing' but not internalizing it.