https://bigthink.com/politics-current-affairs/moral-failings-of-leaders-collapsed-even-the-best-societies-finds-study
Leaders who failed to live up to the moral standards of their predecessors seem to be a common theme:
The study's lead author, Richard Blanton, a professor emeritus of anthropology at Purdue University, thinks that the degradation of such societies could have been anticipated and even prevented, but singular leaders managed to shake them up to the point where there was no turning back.
"We refer to an inexplicable failure of the principal leadership to uphold values and norms that had long guided the actions of previous leaders, followed by a subsequent loss of citizen confidence in the leadership and government and collapse," pointed out Blanton.