Presidential Salary

When reading the section on the executive branch I was shocked by the salary of the president. I know that being President is an extremely difficult job and deserves ebing well payed but to me $400,000 a year was surprising. When I really thought about it I realized by the time the president leaves office they could be a millionaire. While living in the white house they have little to no expenses which means they can save all of the money they make. What I want to know is why U.S. citizens who are suffering during this economic time are having to pay more taxes while the President continues to make $400,000 yearly.