To elaborate your elaboration:

To do money pumping on a grand scale, you have to be in the financial markets; but there are no money pumps there which aren't being busily pumped away. ('Bears make money, bulls make money; pigs get slaughtered'.) This is true for pumps like casinos, too - lots of competition.

And most ways to make a money pump in other areas have been outlawed or are regulated; working money pumps like Swoopo (see http://www.codinghorror.com/blog/archives/001196.html ) are usually walking a fine line.