One reason why someone may find it difficult to believe in politicians is the regular denigration that they receive. It is imperative to understand that statecraft is a valuable and worthy vocation. If someone believes that all politicians are corrupt; that all the policies are corrupt; that every politician is self-interested, then they have given to statecraft a nature that it does not possess. Administration of any institution is and always has been quite difficult, and sometimes thankless. If one has doubts, I suggest that they find some - even small - gathering of humans and that they attempt to guide this community in the most meaningful and just manner. Those who will benefit most from the most just policy will protest vehemently about arranging the group in such a way as to benefit themselves. It is a strange act to witness whole groups rejecting completely those who would preserve the best parts of society, and some of those rejectors, maybe the majority, reject because they believe not that "absolute power corrupts absolutely" but because they believe and act upon "power corrupts absolutely." They incapacitate themselves and then protest that they have been incapacitated.
There is virtue to virtue ethics. They need not exist in the manner they did in the ancient world, since the notion of a strict competition that aims at the most excellent way of living degenerates into systemic and painful corruption. Compulsion supplants an attempt at perfection. That it did in the ancient world. Their systems of administration were intractable and quite stiff, to the point of policide at times. One must attempt always to become better, to expand the justice that one serves to themselves and to others, but that does not mean one must suppress, limit, contain others - not at all.
It is you, my friend, that they meet at times. They witness your entropy and they are aghast at its terrible transformation. Still, you are there - creating them and acting.