Nobody thinks about the spare tire until the worst day of the trip. Build backups while the road is smooth.

Redundancy only gets built during the calm, because during the emergency there is no time and no attention left to build anything. The trouble is that calm is exactly when a backup looks unnecessary, so most people are one failure away from a crisis. Preparation always feels like a waste until it does not.

Pick the single point where a failure would hurt most and put something behind it. That might be a second income, a copy of the files, or a person who knows how to do what only you do. Do it while nothing is wrong, since that is the only time it is possible.