I have a high capacity M.2 SATA in my computer. It's 4TB which I think qualifies for high. I bought it because I found out about that empty slot in my computer and wanted to fill it, not because of a particular need. Having a rare part in my computer gives me an indescribable sense of joy. And don't worry it's entirely used for extra redundancy so I won't lose data even if it dies.
From what I can tell, this was true when it was written, but has changed since with the Samsung QVO 8TB SATA only at a roughly 25% markup compared to a 8TB QLC M2 2280 drive. When I searched last winter it was 2-4x expensive as soon as you crossed the 4TB mark, with 4TB and under being similarly priced between SATA and nvme drives.
To properly design a computing solution, first you define the requirements, and then you select components with specifications that will fulfill your requirements.
If you try to work backwards, you are destined for failure. Dropping big cash on 16 high-capacity SSDs just to ham-jam them in an old system is a really really dumb idea, especially if you're concerned about IOPS.
Just make sure to still back up the data!