The way I got into git was: I was working on a project using Subversion and wanted to be able to work on train rides (and internet connectivity on trains wasn't a thing back in 2007).
Initially I tried SVK, but I found that git-svn actually worked better.
In fact, it worked so well, I stopped using "svn merge" (which took 5+ minutes on our repository for every merge), and started using "git merge" with git-svn instead (which reduced the merge time to <3s, and even the extra git<->svn sync overhead cost only 30s or so). As a bonus, git also reported fewer "merge conflicts" (svn at the time had issues repeatedly merging from a branch to trunk).
So when I ended up picking a DVCS for another project, git was the natural choice since I already knew it. I imagine there are a lot of developers who started out on SVN and took a similar route to learning git, so having a high-quality Subversion bridge turned out to be one of the critical features on the road to adoption. This advantage in adoption then snowballed via forges like GitHub.
In fact, it worked so well, I stopped using "svn merge" (which took 5+ minutes on our repository for every merge), and started using "git merge" with git-svn instead (which reduced the merge time to <3s, and even the extra git<->svn sync overhead cost only 30s or so). As a bonus, git also reported fewer "merge conflicts" (svn at the time had issues repeatedly merging from a branch to trunk).
So when I ended up picking a DVCS for another project, git was the natural choice since I already knew it. I imagine there are a lot of developers who started out on SVN and took a similar route to learning git, so having a high-quality Subversion bridge turned out to be one of the critical features on the road to adoption. This advantage in adoption then snowballed via forges like GitHub.