The fastest drive available today is the WD SN850: https://shop.westerndigital.com/en-us/products/internal-driv...

The consumer price for 2TB is $450. $800 is absurd.

This has always been par for the course for computer manufacturers. I used to spec out Dell PCs for the school I worked at. At the time, retail cost for a 1TB HDD was the same price as a 512GB SSD. But Dell was charging double for the SSD.

For me personally, I used to buy the lower-end models with small HDD and RAM, then upgrade them. But that's no longer an option with these machines.

Apple price is always 2x consumer price.

Also if it comes with $600 in cash stuffed inside, that would explain the price. But it's neither of those things.

It's not, although it is ridiculously fast. But most people don't need ridiculous storage performance; they just need the space.

It's not, Apple most likely use TLC 3D NAND. There's no definitive source but the only remaining SLC drives being made are enterprise (and a few at that), and I think MLC is the same by now. (Even Samsung's Pro series moved to TLC)