There was a time when elected officials understood they were servants. Now they believe they are royalty. Once that happened, it was the beginning of the end for We, the People.
It is why direct taxation was not allowed by the Constitution.
The income tax was pushed by Progressive ideologists, because they believed all government was good, more government was better, and any restriction on government was evil.
Progressive ideology triumphed in the 1930's with the election of Hoover and then Franklin Delano Roosevelt (FDR). It was cemented into place with the FCC and Roosevelt's stacking of the Supreme Court with Progressives, while WWII censorship and the FDR administration made sure the radio networks were stocked with ideological Progressives. The radio networks became the television networks. Control over the information flow in Progressive hands meant Progressives maintained political control until at least 1994.
Watergate was an interior and media coup against President Richard Nixon.
In addition to what you guys said, the early congress was not paid a salary. They did have a stipend, but a salary was viewed as something corruptible, since congress could increase their own salaries. With salaries, they make it their careers, as opposed to being equals among the People.