> The middlemen get 90% of the price of a book. Why
shouldn’t the author simply sell his e-book for $0.90 and get it over with?

and yet the math doesn't justify it. selling (conservatively) 100,000 copies (with big-time marketing) at $25 - $30 (to say nothing of paperback rights and other followons), even at only 10%, is far better than selling (optimistically) 10,000 copies online at a buck.