I don't think anyone is claiming that there aren't freely available resources for learning the basics of other fields, so this isn't much of a counterexample.
Re:Don't Glorify Dropping Out
by astrofinch on Sunday December 26, 2010 @07:35PM
(#2041475)
Free graduate-level graph theory book that I found when I was interested in graph theory: http://diestel-graph-theory.com/basic.html
Here are 5 freely available introductory calculus books.
http://books.slashdot.org/books/04/03/04/028253.shtml