You seem to be attempting the rather ill-advised feat of reading PDF files, which are probably formatted for an A4 or US Letter page, on a screen that's 1/6th that size. That's really not a terribly good idea. PDF is not an eBook format, but a digital representation of a printed page. It can only sensibly be viewed on a screen the size that it's intended to be read on.
The Kindle reads Mobipocket format files, not ePub. This is rather well-known. As you say, "do your homework".
Why do people buy "this shit"? Because they buy books in Amazon's really rather nice bookstore, and aren't even aware of such things as "file formats".
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