Why did the Boxer Nationalist want the expulsion of foreign merchants from China?

By 1800, China was a prosperous country with a highly developed agricultural system. China was not industrialized, but workers in small workshops were able to produce most of the goods the Chinese needed. Because China was practically self-sufficient, its emperors had little interest in trading with Europeans. For decades, Europeans could do business only at the port of Canton. Despite pleas from Britain and other nations, China refused to open other ports to foreigners. The Chinese regarded European goods as inferior to their own and bought few goods from the European merchants at Canton.