People can be corruptable, fallible, greedy and unprepared to wield power over others - especially the people that seek out power.
The solution is to build better people from the ground up (culture and education) AND create institutional protections that function during both the absence and presence of substantial political power. I'd argue that, in the USA, we've done neither and appear surprised when it keeps turning out poorly for us.
No, it's not. Trying to reform human nature through some sort of all-encompassing utopian project always and inevitably (a) fails miserably, and (b) itself becomes a vehicle for corrupt power-seekers to pursue their ulterior motives.
> create institutional protections that function during both the absence and presence of substantial political power
Institutional protections formulated correctly are constraints on the exercise of power itself: strict limits on the reach of political power; checks and balances among multiple parallel institutions; mechanisms of public accountability, incentive structures that align selfish motivations with public purposes, etc. This is exactly the sort of stuff I'm talking about.
> I'd argue that, in the USA, we've done neither and appear surprised when it keeps turning out poorly for us.
In the USA, we've wisely eschewed (a) and avoided the disastrous failure modalities that entails, and instead pursued (b) quite extensively, to the point that things have in fact turned out reasonably well for us, especially in comparison to other countries in the world that have attempted the inverse (i.e. centralizing power with insufficient constraints in the hands of the "right" people, who are always the wrong people).