They probably passed with flying colors at time of hire.

It is down the road where there were not as many checks and balances as needed.

It is later on when these guys get angry, jaded, seduced, whatever.
And have access to more sensitive information because of their seniority.

Today the FBI does much more in terms of continual financial examination for all agents.
Many more safeguards were put into place after Hanssen.

I also assume that the FBI has had psych profilers do more work in identifying
potential spies. Maybe there is a psych profile they know correlates with
selling out your country. And being easily bribed.

I seriously doubt Trump will go to prison. I think house arrest is the best we can hope for.
And I am not even sure about that.

I assume Trump would negotiate some sort of deal. He agrees not to run for office.
And give up some of his social media. In return no trial.