The Attorney General is perhaps the most powerful person in the cabinet. AGs can protect those who break the law, and use the full power of the DOJ and FBI to intimidate, indict, arrest, and incarcerate those whom it chooses.
Look at what the Dept of Injustice did to Senator Stevens. He was a fine man, and well respected. But he made enemies in Washington, so they went after him.
It was only after he was defeated in the Senate, and then dead, that this came out:
Report: Prosecutors Hid Evidence In Ted Stevens Case
Why would it take courage to go after the FBI? Because they are our own version of the Gestapo or the NKVD.
They have been blackmailing powerful people for decades and decades.
Everyone in D.C. knows what they are capable of.
The DOJ is dirty, and so is the FBI.
Someone I know very well was persecuted by the Federal "justice" system. If you fall into the sights of a Federal prosecutor, your life is destroyed. Even if you "win" your case, you will be bankrupt and ruined.
What we are witnessing right now, where the FBI had the goods on Biden and his family, and protected them - is just the tip of the iceberg.