I like to use USB Pen drives as backup storage devices. I have two external hard disk, but I don't need 500 GB or 1 TB hard disk: my personal backups are emails, photos, personal files, so 30-50 GB are enough for me = USB Pen drive ! My concern is about their life, if they have to be my backup storage, as I wish. ps: cloud storage is a different way, here off topic.
First, kudos to you for being concerned about backups! USB pen or flash drives were NEVER intended to be used as long term backup storage devices. They were intended for temporary storage and transportation of files; from home to work, for example. And the reason why is they just are not robust (rugged) enough. They can get dropped and/or stepped on or easily misplaced. In some cases, they can get zapped by excessive static just while sliding in and out of pockets. If you save data to them then store the device in a safe place where it cannot be physically damaged, they should be fine for many years. But understand no single backup is good enough. You should have multiple backup solutions AND backup locations. What if your home burns down or is blown or washed away by a hurricane, tornado or flood? So keeping multiple backups on multiple flash drives in your computer desk drawer is not a robust backup solution. A bad guy who breaks into your home may steal your computer, your external drive, then look in your desk drawer and grab your flash drives too. So another backup in the "cloud", your bank's safe deposit box, or at a trusted friend's or relative's house is necessary too to ensure all your important files can be recovered.
So the problem would be only the material aspect, not the length of the flash memory, is it ? ( nothing is immortal, naturally ! ) Naturally ! I already planned it. I live in Europe, so hurricanes or tornados are not a threat, but fires yes. So relatives or bank are my actual resource. For the cloud: may be I'm paranoid, but what if some bad guy uses my personal cloud storage for his purposed ? Not so easy then demonstrate that " those " files were not mine...
If you're paranoid, then so am I. I don' trust the cloud either. I don't believe they will lose my data, but I don't trust they can keep others from accessing my personal information. Data on flash drives is said to last 10 years or more once saved. But note if you continue to use the drive over and over again, it will wear out and that will degrade the life expectancy. Another problem with these devices is there are many super cheap (in every sense of the word) device on the market. I would not trust my data to them.
