Backups *will*, but plenty of people think backups are beneath them, and would rather blame someone else when they lose data.
Computers *always* die. Or take a swim. Or are left in a coffee shop. Or on the roof of a car. Etc.
If the data is not backed up, then it's not important to you.
Exactly. I work in cloud computing, and the mantra is "everything fails, all the time". You plan for failure in your design so that there is always redundancy, failover and automated backups, versioning and restore paths.
How often you backup, and how many copies you maintain depends on the importance of the data.
My personal setup for my Macs is:
1) personal data / work / documents or other important stuff is in folders that are automatically synced to cloud storage (Dropbox, Google Drive or iCloud)
2) Time Machine running locally, to external disk when travelling, or to NAS when at home
3) Carbon Copy Cloner images taken once a week or before any OS update. (creates bootable copies)
4) Additional physical backup disks of important stuff (docs, photos) and stored in a safe or offsite
5) Cloud sync to backup my cloud copies to a secondary cloud storage (so if Dropbox fails, my stuff is also on Google)