I tend to carry a book bag with my all the time and usually my external hard drive is in there. My lifestyle involves going between multiple buildings and homes all the time so it's important that I have my tools and information with me. This means that there are many opportunities in my day for my external hard drive to fall on the ground and become damaged. Often it only takes on drop for the average drive to be damaged and all the data to be lost. I tend to keep backups of my very important data on another machine at home. However, that is not always possible, so losing that information would be catastrophic.