it has been commented about ssd's failing without warning. I have seen that but it is really rare. SSD's do use S.M.A.R.T and it should let you know if you are monitoring it about issues before complete failure.
That being said. If your not backing up data in at least two places other than where your using it your asking to lose it. I use spinney drives to backup my library. One that I keep in a fire proof safe and bring up to date every month or so and one that I do more often. I have a script created just for my library using rsync that I run when I want it to back up. So it is a manual solution and if I get lazy or forgetful I put myself at risk. I have the hardware to build another little server to just use for backups and automate everything but I haven't done it as I don't have enough drive capacity to backup everything that needs it. about 60TB.. for my library yes but for all my other personal and business stuff No. Instead I have a huge stack of labeled hard drives in the 500GB to 4tb range that I break all the data I have up across and I will just drop a drive or drives in an external usb docking station and initiate the rsync job for that drive/datasets.
Before anyone points it out I totally agree that that there are much better ways of doing this. However the cost of doing it right due to the size of stuff to be backed up is prohibitive for me. All my data sits on Big raid 10 arrays on a server, made up of 8tb and 10 tb drives
other than the library that needs it's own nvme for performance. So for most of it a bare minimum of redundancy before the single backup to external drives. Library gets a little bit more in the way of backup. When I win the lottery I will have multiple backups with my own personal off site cloud backup also
For most of you with small library's of under 50,000 books, (well any size iibrary really) you should get an external usb hard drive and use the calibre export all books feature as your backup. Then you should get a large flash drive from a reliable manufacture and do it to that also. Use the hard drive for daily or weekly backups and take the flash drive and put it in a fire proof safe or even better off site at a relative or friends house in a small fireproof safe there. Swap it out monthly. The reason I recommend using the export function is it backups up not just the books but also the preferences, plugins and everything else you have customized in your library. Just copying the library directory and database file with rsync like I do for the majority of my backups will not save a lot of that stuff for you.
now that you have a off site safe. Take and put copies of all your important documents such as Id, birth certificates, titles etc in it also