Our on-prem GH enterprise hasn't gone down in the last year.
Additionally any potentially disruptive work like upgrades etc can be scheduled outside of business hours so that they won't impact users
Additionally any potentially disruptive work like upgrades etc can be scheduled outside of business hours so that they won't impact users
Something tells me that if you can schedule upgrades "outside of business hours", your scale is small (because in a global company, it's always "business hours" somewhere), which makes the cost argument even more prominent.
And any large business will already be doing Backups, DR etc for their existing systems.
Any? Are you sure?
If you work in a large business that needs git but doesn't have backups and has no disaster recovery plan at all you're going to have much bigger things to worry about than a git repo being offline.