You can't make devices that deal with motors and rare earth magnets and spinning platters coated with ruthenium and other rare materials at insanely exacting tolerances, encapsulated in hermetically sealed Helium bubbles for cheaper than you can photolithographically lay out a bunch of NAND gates in cheap bulk semiconductors. There really isn't any word for it other than absurd. And the fact that NAND chips are in literally EVERYTHING means they are commoditized. Which means economies of scale make them cost almost nothing to manufacture. And yet... it still costs you 4x or more to get an SSD rather than several pounds of spinning metal? Nah, that's not how things work without help.
Why stop with microwaves? Why not make platters out of pure gold and the read/write heads out of synthetic diamond? Maybe integrate a cryogenic cooling system and store the data in a Bose-Einstein condensate? At this point it seems people will believe even that is cheaper than some NAND chips run off a line like printouts.
Western Digital's gross margins are 40%, while Micron's gross margins are around 46%. This suggests that the margins of both NAND chips and Spinning Hard Drive rust are roughly equivalent at current market prices (at least, within a magnitude or so).
Large-scale manufacturing turns out to be efficient. At the moment, prices suggest that Hard Drives are indeed far more efficient to make.
If your hypothetical were true, then we'd expect Micron's gross margins to be larger. From my understanding, the high-tech NAND gates have a relatively low yield. Yields on bulk semiconductors are no where near as good as the yields of Hard Drives.
If Google can make their own processing unit just for running ML, why aren't they also making their own SSDs to drastically decrease storage costs and improve storage performance?
There are only a handful of fabs making the required NAND chips. Spinning up a new fab takes years and hundreds of millions of dollars, not to mention some serious technological and manufacturing know how. So it's really not easy for someone to just up and enter the NAND market.
I don't exactly doubt that price fixing is happening, but my understanding of current high SSD and even RAM prices at the moment is that there is a serious demand that outstrips the current fabs abilities. Mobile devices are eating up a lot of the NAND output.
In the case of GPUs they can turn a defective GPU into a lower tier GPU by disabling malfunctioning components, which means that it isn't a total loss. I doubt NAND chips can be salvaged in the same way. Since they are so simple, there's nothing to recover. It goes straight into the bin.
NAND does actually have a degree of flaws it can tolerate as they are made today in consumer SSDs. I am not certain, but SLC Enterprise SSDs made for database servers and the like might get the best yield chips I'd guess. On consumer grade devices, there is an amount of 'slack' space that the chips actually can accomodate that is used for relocating data from damaged areas, wear levelling, some bookkeeping, etc. So if you buy a 1TB SSD, there might be enough actual storage on the chips to hold 1.1TB if all of it was made available. I'd not be surprised if particularly bad runs come out and get binned as 512GB devices because large portions of the chips are unreliable.
Kinda like how ladders are rated: they say 300Lbs .. it'll probably take more than double that - but if it breaks when you overload it, the manufacturer can point to the rating and say, "you exceeded its spec"