> It should at worst scale linearly with user-count
No, front-line support staff might scale that way, but organizational costs scale superlinearly with the size of the bottom of the pyramid, so even if it did, total cost would be super linear with userbase.
Users can be free or paid. When I open up support tickets backed by a paid account they're always very quickly resolved. I'm not sure how much GitHub needs to support people who won't even pay for the product...
