The DJIA has gone from 89 to 15k because of the labor and ingenuity of American employees and entrepreneurs. New companies come out with new products, these products meet consumer needs, this creates value, this value is reflected in the company's earnings, and corporate earnings are reflected in the stock price. None of this happens because some quant sits at a computer and programs in mathematical models of prices. If Coca-Cola was still trading at 50 cents with its current earnings, everyone - financial professional or not - would be jumping on it. It wouldn't stay at 50 cents a share for long.
Some sort of stock market, with decent liquidity and abundant information, is necessary for proper functioning of the economy. But the stock market we have, where hedge funds colocate boxes on the exchange so that they can execute trades within milliseconds of new information coming in, is overkill. I think it's really sad that so many of the best and brightest minds are drawn into competing with each other instead of creating value for others.
I feel the same way about law, which is another necessary-but-zero-sum profession. It also tends to attract really smart people, perhaps because really smart people are used to being smarter than everyone else. The link to tournament economics that someone posted on another article here is quite appropriate.