Why?

...why do we expect those so-called leaders (politicians or whoever), to possess nobler personalities (or we say or argue or write so)? Haven’t we in this system already implicitly agreed that it’s acceptable for them to work for their self-interests as long as that doesn’t cause serious harm to all of us? The trick is, behaviour that may create catastrophe to all of us doesn’t seem dangerous at the beginning, especially to those ‘corrupt’ beneficiaries...so let’s drop the false expectations & ideals, stop unrealistic assumptions & arguments & education that often lead to subsequent disappointment & resentment...and focus our energy on the efforts to innovate & re-invent the system into a more incentive-compatible one...