I always do some level of RAID. If for no other reason, I’m not out of commission if a disk fails. When you’re working with multi TB, restoring from a backup can take a while. If rapid recovery from a disk failure is not a high priority for you, then you could probably do without RAID.
Either way, make sure you test your backups occasionally.
Another way to put it: With RAID, a disk failure is like your Check Engine light coming on. You can still drive, but you should address the problem as soon as you can. Without RAID, it’s like your engine has seized up and you have to tow it for repair and are without your car until it’s fixed.
Malcolm hates everything, lol. Except pineapple and when T’Pol calls him “stinky”.