Money is not the only factor. IT informs me that we are getting great support from github for our enterprise instance. As a user I have no clue what support means, but the people in IT are the ones getting that help.

So long as gitHub provides value we will stay there. Support is worth it when several thousand developers get an unplanned paid vacation every time a server goes down (of course git is distributed so the a few minutes of downtime will affect nobody, but much more than that and people notice).