The goofball WD Elementals/My Books and Seagate One-touch/Expansion eternal drives are for the masses to have cheap local storage.
I agree they don't buy many internal drives now, but the EXOS and DC drives are made for the data centers. I assume the street prices of those are based on supply/demand for that sector and there is some seepage into the consumer market from larger system builders that buy in bulk and resell.