I decided to move all my private repositories to my own server. When you do this, make sure that the server has continuous backups. Also, make sure you still have an offsite backup. Once you figure out what these things are worth, you may realize that you should probably just keep paying Github.
Given the decentralised nature of Git, having continuous backups becomes less important unless all my computers (including the server) fail at once.
But yes, backups are important, and they are done.