You don’t have to (though it can make sense, but I’d encrypt everything and have an additional backup). Another fairly straightforward solution (in that there is ready-made hard- and software for it and doesn’t need much maintenance) is to use a NAS with RAID 5/6, and to have a second NAS at another location (can be a friend or relative — and it can be their NAS) that you auto-backup the first one to over the internet.