The correct answer to this open question is the following.
A major reason why Watergate left many Americans upset with the government system was that people became more skeptical about politics and less trusting of government.
On June 17, 1972, many people entered illegally into the Democratic National Committee in the Watergate Complex in Washington D.C. to steal important documents and wiretapping telephones. They were arrested on the site. Watergate scandal had commenced. Richard Nixon tries to cover the conspiracy but it was revealed in August 1974. After that incident, people became more skeptical about politics and less trusting of government, and Richard Nixon was impeached.