We should not have to worry about our elected officials profiting off of their positions. We should be able to trust that those we send to Washington to represent us will do just that, and not be swayed by anything other than that responsibility.
Politicians, like all people, have a propensity to grow more corrupt the longer they remain in power. Politicians are always susceptible to corruption, but the longer they remain in office, the weaker the shield of good intentions becomes. Because the system in Congress is largely based on seniority, the longer politicians remain in office, the more power they are able to amass.
Newer leaders will have less knowledge of how to exploit Washington and its lobbyists for personal gain, and fewer opportunities to do so. Term limits will help keep representatives more focused on serving the people and less focused on serving their own interests.