Raid is fault protection not backup.
Backup means something u saved incase something fails.
Fault protection means just that, its protection against faults and hardware failure.
How important is the data? Most people use cloud as backup, which they are basically enterprise level fault protection vaults.
I personally use a RAID-Z2, which allows me to have 2 drives fail before it gets really dangerous. (fault protection)
The Odds of 2 drives failing before a resilver can be done are slim, unless someone decided to physically take a hammer to my server.
Then the really important stuff is backup'd and goes on a USB HDD, and is taken to the office.
NAS's are really good at fault protection, but it shouldn't be the only form of backup if the data is important.
Taking a external mirrored USB drive, backing up all that you need, and then shelving it somewhere safe with power off, can be a cheap viable solution if you do not want to cloud.