left.. Seagate and WD.
My Seagate 2 TB external hard disk just died (a slower death so I was able to get some critical files off).
and I replaced it with a 4TB WD passport.
I tend to run backups routinely to my RAID 8+2+2 storage server (which has lost 1 out of the 12 drives so far).
I don't have (but should) some sort of offsite backup (in case of fire or theft or earthquake).
Full disclosure, I used to work for Seagate and I've been in computer storage for most of my now long career in computer science. I was Chief Architect at Seagate.
Hard drives die. Run RAID (redundant array of in(expensive/dependent) disk) or use erasure codes or a service (cloud storage) to backup critical data. Multiple copies are good too. Most things downloaded from the internet can be downloaded again.
As a last resort, there are services that can possibly retrieve your data from a failed hard drive (depends on the mode of failure). They aren't cheap.
One other tip... I use Defraggler to examine the "SMART" data from my attached disk. Look at the "health" tab... if you see any of the reported error rates start to move ( especially "uncorrectable sector count" or "read error rate" or "seek error rate" ) then I would be in the market to replace the drive.
Also monitor the temperature of the drive... they are mechanical and don't do well if they overheat.
Not to mention shock forces (by dropping them or moving them while operating).