Power is an aphrodisiac but one that never satisfies.
More is always demanded. That is why boundaries and controls are always defined for delegated power.
Private vs. Public Sector Incentives
It is extremely difficult to monitor and control power. Control requires nearly constant oversight. Violations must be punished to reinforce boundaries.
The private sector does this effectively as profits are the standard by which all departments and personnel are measured. Violations are usually met with demotions, terminations and/or criminal prosecution.
The public sector has no similar standard. It is a bureaucratic model that is controlled by rules and regulations. Bureaucrats have little incentive to innovate or make improvements. Numerous studies suggest that most bureaucrats desire to expand their staffs as it makes them more important.
Change in a bureaucracy is not welcome. Most bureaucrats are content to keep their heads down and stay within the rules. Such behavior is optimal.
When rules are violated, it is easy to overlook them or issue mild rebukes. Rarely is anyone demoted, terminated or prosecuted.
Political motivations also play a role. No Administration wants to call attention to malfeasance on its watch. Ignoring it, unless it is publicly known, is both easy and politically optimal. There is little motivation to criticize or punish fellow bureaucrats.
Standards Deteriorate, Especially in Bureaucracies
Those with power resent oversight. That goes for presidents, elected officials and others in the bureaucracy. When those with power also have a veil of secrecy covering their activities, it is easy to bend rules. Bending rules without criticism merely resets these rules in the eyes of the violators. Over time, standards degrade and the lowered standards become de facto standards.
What once was considered out-of-bounds becomes normal. Over time, this process repeats again and again until behavior becomes so egregious that it becomes impossible to ignore it. That is the point that has been reached in the Deep State scandal involving Donald Trump.