Backups help prevent lost work, but they also ensure your data is always accessible.
Having a complete copy of your repository (saved externally) protects you from relying on external services, i.e. GitHub. After all, no service can guarantee 100% uptime. Thus, even in the unlikely event of a GitHub outage (which has happened!), you’ll be able to access your repository’s data. Automated backups ensure your data backups are always secure, up to date, and easily restored. After all, a backup you can’t restore isn’t much of a backup at all.
Learn more about backups for GitHub here!