Why did charles beard believe that the constitution was written with economic interests in mind?

Charles Beard believed that the constitution was written by a group of rich people with economic interests. Beard believed that the reasons were financial interest and called the constitution a counterrevolution of the holders of bonds against ordinary people, farmers, and debtors. I argue that the Declaration of Independence and the Constitution were not the true motivation of the editors and were trying to protect their wealth. The authors were rich and powerful men who did things like allow slavery to continue and the contradiction of their speeches.