These 2 solutions cost less than 10 USD/month: Jottacloud [1] and zfs.rent [2]. The former is even hosted in privacy-friendly Norway, and its 5 TB unlimited with going over that you get upload-capped. So I pay 90 EUR/year for Jottacloud. Which is approx 10% of your projected 1000 USD.
zfs.rent is an interesting model, though quite beta and currently not accepting users. And those prices add up pretty fast. Let's say you want to back up about 4 drives of data. That's $960 a year for the first two years, then $480 a year after. Or if you want any redundancy at all, $1200/$600. You'd probably want to find your own cheaper box to stuff hard drives into, and at that point you're far gone from "cloud".
2. You can build a 8TBx4+2 raidz2 with EasyStores for $720. Backing that up to a raidz1 zfs.rent is $1200 for a single year. $2500 for 3 years by prepurchasing the drives.
An estimate of $1000/year for full cloud backups isn't wrong.
If I had an amount of 24 TB to back up I'd buy my own server and harddisks, and I'd physically set that server up at work or at home. Then, travel to the data center (I live in Amsterdam Area, so enough choice) and put the server there, again, physically. No need to "upload 24 TB".
RAIDZ et al. is about availability. Which makes sense for businesses, but for personal data an offsite backup makes more sense. I'd just go with a mirror of 2 different disks, with different serial numbers (ie. different orders).
But using that pricing, 24TB with Jottacloud would be 450 EUR/year, which is still on the order of $1000. The larger point is that disk sizes are always growing, and while 24TB may seem unnecessary to you, it's very easy to build an array that is cumbersome to backup. And IME this has remained true for the past two decades.
You're right that the cost effective way of performing large backups seems to be just buying another array and hosting it somewhere offsite. But that still doubles your array cost, and so is not something to be done lightly.
FWIW personal users want availability too, unless rebuilding arrays from scratch is your hobby. A simple mirror is a form a raid, which you can only get away with if your storage requirements can be taken care of by a single spindle. If that's where you are, fantastic. But that doesn't describe most home ZFS users.
So for 24TB you would use two accounts, assuming they're fine with that, and your uploads would run at 5Mbps per thread, with 12 threads in parallel.
That will let you upload 100GB every 4 hours, which should be enough. And the total cost would be 180EUR/year, which is pretty far from $1000.
https://www.cloudwards.net/backblaze-pricing/
It does sound good. :)
Its also just the first backup which takes a (long) while. If you got only 10 mbit upload, then you're able to upload 600 mbit per minute, or 36000 mbit per hour. Which is about 4500 mB/hour (or ~4,4 GB/hour). Which results in 108000 mB/day (or ~105 GB/day). Its about 3/4 of a TB a week.
I'm glad I got 30+ mbit upload with my VDSL2. My first backups took ages (I got 5 TB with Jottacloud). First I thought it was Duplicati being slow with regards to cryptography or being .NET, but nope that ain't it.
Incremental backups during night are not going to hamper the connection though.
That's best case. Anyone who's done large transfers over the internet knows reality will be much worse.
The point is that home users can have good reasons for relying on redundancy.
Targets:
1. That NAS off in the corner built from an old desktop.
2. rsync.net and similar.
3. your encrypted cloud backup service of choice, through an adapter.
If the value of your data is less than the cost to protect it, you know it is disposable, you just wish it weren't.