[TheGorramBatman]

There are several textbook writers who have made significant profits from their books. James Stewart of Stewart's calculus fame, for example: http://www.thestar.com/news/gta/2011/02/04/the_house_that_ma...

[dalke]

The qualifier "such a book" referred to the original description "Not undergraduate ones, but the really narrow topic ones that are used in graduate classes as reference materials for professionals".

That excludes Stewart's calculus, and many others.