Where's the value?
I can't believe the punters are that stupid that they think they own all the code in github.
Since most of the accesses to github are via git - and very few via web browsers - there's very little exposure for advertising revenue.
Since it is so easy to replicate a git repository, there is no real "stickiness" to git either. In 5 minutes I can move my repo elsewhere.
Yes, a small service business makes sense, but $2bn no!