Even if they have great infrastructure, this article is evidence that they can still take you down at any given moment if they so much as feel like it.
You need those database backups.
You need those database backups.
I haven't checked GitHub specifically, but most of those terms include, "and we can ditch you any time for any reason, maybe with 30 days notice if you're paying"
If you want to take advantage of their infrastructure, that's fair, I understand, but at the very least, run some tooling to backup issues, pull requests, wiki pages, etc on a regular basis.