We are digital librarians. Among us are represented the various reasons to keep data -- legal requirements, competitive requirements, uncertainty of permanence of cloud services, distaste for transmitting your data externally (e.g. government or corporate espionage), cultural and familial archivists, internet collapse preppers, and people who do it themselves so they're sure it's done right. Everyone has their reasons for curating the data they have decided to keep (either forever or For A Damn Long Time (tm) ). Along the way we have sought out like-minded individuals to exchange strategies, war stories, and cautionary tales of failures.
If you're putting them in RAID make sure the drives are designed for RAID and the OS/File System can pass the TRIM command on to the SSD's.
You can always get a case like this: https://www.amazon.com/dp/B003IIBO56
And mount four of these in there: https://www.amazon.com//dp/B00V5JHOXQ