As this phenomenon is so common, do we have enough science about it to make it a base for laws, so future generations could avoid this state of collective psychosis it seems to lead to?
I think it is widely accepted that power corrupts. It is the basis of democracy, and why we would defend it so jealously. Democracy was fought for and won, and we should never forget the alternatives are much worse. This requires peaceful debate, free speech, and free and fair elections.
Term Limits.
Alone they fix nothing. You need systemic action behind them to avoid creating a shadow government that just puts their next puppet in place.