I mess up with negatives (too) often, but good negatives will last long. The poor ones can be saved by scanning and adding some photoshop magic. Ofcourse not always.
The worst scenario for negatives, prints and my digital files is physical damage. Flood or fire...
The paranoid would always have good prints from best negatives stored somewhere safe place. Same goes with digital pictures. Best quality prints well stored.
I don't have such a masterpiece in my photographs that those precautions feel necessary.
The main concern will be in ordinary family photos, and archiving them is just way too much work.