The most vulnerable is portable hard drives. Their poor heat dissipation and susceptibility to knock and vibration significantly increase the chance of failure of spinning disk hard drivers. For spinning disk hard drives inside a desktop computer, their life can also be shortened by cycles of turning off and on. Leaving PCs on 24/7 is bad for electricity bills and the environment, but it's kinder to the hard drive.
Spinning disk hard drive can give warning before they completely fail, if you turn on S.M.A.R.T. There is also a small chance of the data being recoverable by professionals. SSD, however, rarely give any sign before sudden total and irrecoverable failure.
People don't do backup because it's a bother, and it's always something they'll do later. Best way is to have a system that's set up once and then runs automatically. You may want to periodically practice a data restore to make sure the backup works, though. When I setup mine, I researched the options and decided on BackBlaze - a well established online backup subscription service. It's been working hands free and flawlessly since.
Offsite or online backup is the best in case of catastrophe at home. You can have some secondary backup at home, which would make restoration of large amount of data quicker. For that, get a NAS (network attached storage) the supports RAID (Redundant Array of Inexpensive Disks). RAID stores same data in copies across multiple disks. A single disk failure will not result in data loss, and will give you a small time window to replace the failed disk. Multiple disks failing simultaneously is quite rare. You can even set up RAID to be tolerate of 2 disk failures. With a NAS, you can use TimeMachine on a Mac to do the backup. For windows you may need to find a 3rd party backup tool.
These days, cloud storage for documents of everyday work is quite prevalent and handy. iCloud, OneDrive, and Google Drive are all easy to use and well-integrated. The caveat is the amount of storage is limited for free version and can go up quickly for large video files. In addition, these cloud services tend to sync files frequently, and a large file upload can backlog syncing other files you are working on. Backup like BackBlaze are usually scheduled to run in the hours that you don't use the computer, and their price per terabyte is quite a bit cheaper.