I have true 3-2-1 backups on a server running proxmox with 32 cores, 96gb of ram, and 5TB of ssd disks (2TB usable for VMs). Cost me $1500 for the new server hardware 2 years ago. Runs in my basement and uses ~30w of power on average (roughly $2.50/mo). The only cloud part is the encrypted backups at backblaze which cost about $15/mo.

Its a huge savings over a cloud instance of comparable performance. The closest match on AWS is ~$1050/mo and I still have to back it up.

The only outage in 2 years was last week when there was a hardware failure of the primary ssd. I was back up and running within a few hours and had to leverage the full 3-2-1 backup depth, so I am confident it works.

If i was really desperate i could have deployed on a cloud machine temporarily while i got the hardware back online.

If you self-host your NAS, then your server has access to the data in clear to do fancy stuff, and you can make encrypted backups to any cloud you like, right?

Some people I know make a deal with a friend or relative to do cross backups to each others' homes. I use AWS Glacier as my archival backup, costs like 3 bucks a month for my data; you could make a copy onto two clouds if you like. There are tools to encrypt the backups transparently, like the rclone crypt backend.

You don't need homomorphic encryption for a backup, normal encryption suffices.

I keep a small backup drive at my office which I bring home each month to copy my most sensitive documents and photos onto.

All my ripped media could be ripped again: I only actually have a couple of Tb of un-lose-able data.

FHE is so much more expensive that it would still be cheaper.