I continually hear people expressing this sentiment, and it has never seemed true to me. If work is defined as "effort over time", then how could someone like Bill Gates live long enough to earn his fortune, relative to that enjoyed by other people? Many doctors, example, seem to put more "effort over time" into their careers, without ever gaining anywhere near the sum of money Bill Gates enjoys.
Bill Gates obtained his wealth, not because of his own "effort over time", but because, in accordance with the conventions of capitalism, he networked himself into a position where he could compel others to sign a portions of their "labor over time" to him via contract. As long as this practice isn't pushed to its excesses, I don't have a problem with it, but getting wealthy through good networking is a significantly different process than earning your money through hard work.