Alan Greenspan acquired too much power and went out of his way to railroad regulators. It was a classic "absolute power corrupts absolutely" and his flooding the markets with dollar liquidity at every crisis completely destroyed any concepts of moral hazard, of which we are still living with the consequences to this day.

He set the stage for the financial crisis that started crumbling a year after he left the fed chair. It wasn't all his fault (politicians lost any spine and bankers any sense), but he was the conductor.

And when production for a system I built burns down the month after I leave my job, the next guy they hire was actually the culprit! Greenspan was seen as responsible for the dot-com bust as well which was solidly in the center of his tenure.