That 10TB drive is 100% fake! Amazon is full of fakes.
A good rule of thumb right now is $60/TB, significantly less and you're approaching fake territory.
I should be clearer - that drive is fake if it's an SSD, it's a normal price for HDDs. Cost per TB of HDD isn't linear, though, it's a bit of a bathtub based on drive capacity and feature set (e.g CMR vs SMR)