It is a typical mistake of a novice regarding computers is that they will never break on me.
20 years ago when I started Trainz I read a saying about hard disks:
There are two different types of hard disks, those that have broken and those that will break.
All content that is valuable to us needs to be backed up with multiple hard drives or pen drives, and even of different brands.
I have all my old scanned photographs, documents and invoices stored on three external hard drives of three different brands, in case of unforeseen failures.
Not only do I have backups here, I routinely make a backup and put it at a friend's home......if this house gets destroyed, the backup at their home will restore 95-100% of my stuff.
Disk problems should not cost a whole new computer, if you have a nice one. Just buy a new disk drive and get someone to clone your current disk (Sans errors) to it or do a fresh install.
Hopefully you have a USB recovery drive. With one of these you can just reinstall windows on a new disk drive. Saves buying a new machine. If you have a backup as well with a system image that works. If you buy a new hard drive the manufacturers have disk cloning software so you can clone a c: drive.
While I'm impressed with your multiple layers of redundancy, I have to wonder if it's a bit overdone. If your livelihood depended on Trainz I could see it could be a good strategy but I think for most of us it's a game, a hobby, something to have fun with. One backup yes, perhaps two for extra safety. Unless they are all automatically updated with the latest changes, that's a lot of work just in case a random 6 all fail at the same time and you only have one to recover from.
He says he's replacing his computer. Some people get the physical computer and hard drive mixed up. I dealt with that a lot in tech support among the users. It was annoying because I pictured needing to order a hard disk if under warranty and hopefully recovering data depending upon whether this was a manager or not. When I visited the users, it was their actual PC died due to a power supply or bad RAM - a totally different problem.