This guy doing some flying trapeze dunks on the reporter right out of the gate. 
I've had multiple professors assign their own books, and they were all well written and decently priced? Feel like a much bigger issue is the first-year mandatory textbooks that come with a single use code for assignments/quizes and are forced on the faculty by the administration. Those usually cost at least 3 times as much, and is content you can find easily on youtube. Feels like it's intentionally focusing on something that feels vaguely "corrupt", but it costs students a lot less than the backroom deals with textbook publishers.
Why would a professor who is enough of an expert in their field to have published a book on a topic assign it for a course they're teaching 
Very mysterious, probably they're ontologically evil
"It is a form of money laundering," the Berkeley student told Insider. "It demonstrates the power structure of college classes." lol top tier trolling