When I see the mostly young people of Occupy Wall Street - a mixture of the bored, the nihilistic, the seekers of excitement, the left-wing true believers, the confused idealists and those hoping to engage in violence - railing against the rich capitalists on Wall Street, I get worried. Because the hatred they express toward the rich is similar to that expressed against the rich by Stalin, Mao and Pol Pot. Of course, these people are not comparable to those killers. But class hatred must lead to bad things. That is why President Obama is playing with fire with his attacks on the rich.