Not sure how profitable GitHub is, but there are users paying for private repositories or for the Enterprise version and the revenues thus far seem to be enough to support the free users as well and to an outsider like me being a win-win situation, since GitHub is now the place to be on, with open-source projects giving them free exposure, with the Enterprise version starting to win against other established solutions because "everybody knows GitHub". I used to be a paying customer of GitHub, now I'm enjoying the free benefits and pushing for the Enterprise edition in my organization. Am I the product in this case?

I do hate the "free to play (with gouging IAPs)" model and I actually prefer ads with an option to go ad-free. However even with this business model there are heroes. See for example Path of Exile, a free game in which the in-app purchases do not have an impact on your ability to win: https://www.pathofexile.com/

I do agree with you, the chosen business model makes the difference. I do believe that ads aren't inherently evil, it's just the status quo that is. Yes, today ad-supported means that we are the product, but this product has a free will, a fact that some companies are forgetting. At the very least there are some signs of change. Google for example is at least trying to play it both ways - you can be a paying customer of Google Apps and they'll introduce subscriptions to YouTube for going ads free (with the ability to cache content for offline viewing on mobile devices being the incentive needed for regular folks).