The question I ask is myself this: Suppose one day as a proprietary software developer, I setup an outlet. This software program functionality I wrote took many months to create, thus am looking at some commercial value to cover costs and try and make a some profit, if it is successful. 

Next to my outlet, arrives someone who saw the potential of my software and found a free alternative whose source code has been opened for small touch-ups. He/she is looking at the same market segment as I am but offering the software for free, with only charges for support.