Those are not mutually exclusive positions. Software can be open source (or even free software) and still be commercialized.
In our case, we made all of our products open source for a number of reasons, some ideological and some pragmatic. Whether or not that proves to be a good decision from a financial standpoint remains TBD... but the important thing is, it doesn't matter. If we never make a dime from what we're doing, we'll all have benefited from the process in other ways. And we'll have contributed something to the world that somebody may gain some benefit from one day.
Beyond your team, does the community contribute to your product in meaningful ways?
All of the above, of course, applies very specifically to the code we have written. But here's the thing.. SO much of what we do is based on building on top of, or integrating with, other open source projects, that - by a more inclusive standard - we can say we've received a ton of community contribution. And that goes back to the one of the ideological reasons I mentioned earlier. I would feel like a complete hypocrite to reuse so much work done by others, and release it as part of a proprietary / closed source product - even if the license allows it.
Third party contributors whose work is included in commercial sales would then be given a portion of the revenue from those sales.
Private individuals, or non-profit institutions, can still use shared source software. A few might be put off if they think it won't help them to find a job, but even they will think twice if companies start paying to use it.
Having popular software is nice, but it doesn't pay the bills if you can't charge for it.