Thom Hartmann says that he makes his living by producing services for the general public through his talk shows and writings, whereas investors like Mitt Romney make their money by investing in other companies. When those companies do well, so does Mitt. When they lose, so does Mitt, the differences between producing and investing.
I wouldn't go as far as Mr. Hartmann here and tax all rich people at ninety-percent. If you want people, to be doctors, lawyers, accountants, mechanics, business people etc., to be productive and successful then you shouldn't discourage them from being successful. You shouldn't tax the hell out of them simply because they are successful. I prefer taxation by the income you spend rather than the income you earn.