That's exactly my point in wondering about the ratio of students to established company professionals.
For every company I've ever worked at, the "community" or "network effect" of a source control vendor is meaningless. Because the repos are all private. Sure, the company might have SOME open source stuff mirrored on GitHub for publicity purposes. But the real bread-and-butter daily WORK that pays the bills takes place in private repos. In most cases, private repos that are hosted on-prem rather than in the cloud.
Sure, GitHub and its "network effect" matters for open source projects, and for resume-fodder side projects we tinker with as individuals. But all of that is free anyway. What about the scenarios where you'd have to pay GitHub a lot of money? How many vocal people on HN are actually IN that scenario?