I rarely have geeky conversations with anyone (since I don't know any and that is why I hang out here) but I'm genuinely curious: Why is git more popular than hg? I tried both and hg was generally easier (for me) to pick up. I'm sure it's not JUST because of github.
2) Cargo-cult computing.
3) Very strategic integration with Heroku and Xcode. Both are very important force multipliers. It was initially the Ruby folks they were the champions of Git outside of the Linus kernel devs.
4) Github.
5) Silicon Valley. SV is a very large echo chamber, the fact that Github is in the middle of it gives you an edge. Bitbucket is based out in Australia I think, there was less people to talk to, less good people for hire etc. Back in around 2008, both Github and Bitbucket were terrible.