You are not working in this industry, are you? I don't know about you, but Open Source doesn't pay my bills...not a single cent.
Then you're doing it wrong
There are two sides of Open Source Software (I've yet to find my side - leaning towards 2...)
1 - Those that want the whole product Open Sourced
2 - Those that only want the code Open Sourced
Going with 1, you need to make your money on something else than the direct sale of the product. Service and Maintainance spring to mind...
Going with 2 is *way* more simple to make money off - You open up the source code, in the hopes that others will join on the coding frenzy. Some might say that you should open source just because (!), I like to think that it is because you get something back.
Case in point: lwjgl. It was being actively developed on win32 - and then all of a sudden Elias shows up with a linux build - and *everybody* immediately benefits (well linux users do
Going further along lwjgl was in the beginning just a gl mapping with some other utility stuff thrown in (might be oversimplyfing stuff here...). Because Cas decided to fork his work of as an OSS project, he has (and indeed the whole community) for "free" gained a more stable product, with loads of more features added (OpenAL, Linux version, Mac OS X version, Controller support etc. etc.). This can then in turn be used in a commercial project (be that OSS or not).
In the case of Alien Flux (Cas's commercial project), some might argue that you shouldn't just open up some parts of the game, but indeed the whole game. I tend to fall on opening up n% is the better solution since:
1 - No reason to open up all the code since this doesn't make sense (for whatever reason)
2 - Much more simple to make a sane buisness plan
ps. Would be nice if Cas would join in on the discussion of using OSS to do a project... ?