SSD's are cheap nowadays. They're also much more reliable than HDD's. That said, when they fail it's usually catastrophic failure with total data loss.
If your data that's important to you, I would still use redundant storage. Especially since the cost is minimal.
The cheaper SSDs can be very failure-prone though. I actually use second-hand spinning disks in my server and I have a whole bunch of spares waiting in the wings. I am still backed up though.
Had a Kingston SATA SSD that I had used for my plex server data (not media), and it ended up dying on me. First drive I had actively fail on me and cause data loss.
That's interesting because Kingston's usually have a reputation that proceeds them. I currently have some cheap Chinese knock-off SSD that I've put through hell and it keeps plugging away.
That's the entire problem with those knock-offs: almost no quality control. So it can be very hit or miss. Bottom line is that if you care about your data, you'll back it up! 😉