What's wrong with those things? Obviously books costing $70 or $100 are not priced to target people subsisting on ramen noodles. And it's only the current debt-madness which has lead people to think those prices are anywhere near sane.
Like most things, no one is getting terribly rich off textbooks. What bothered me most in college was when they would release a new edition and refuse to buy back the old one.Even when the difference between the versions wasn't noticeable.
That dollar in the PDF is sliced so many different ways and spread apart that you don't really notice that the publisher takes 64.6% of it. Of an estimated 6 billion dollar market. I'd say _someone_is getting rich off textbooks, but it ain't the author.