Incompetence, among other reasons. Also using his positions for political purposes. An article at American Thinker reveals a lot. Below is a partial list of Comey’s ‘Errors’. How many do you remember?
Comey’s fitness report while heading the FBI is a compendium of incompetence, and dissembling, beyond his blockade-running interference for Hillary’s email felonies, and AG Loretta Lynch’s deliberately compromising encounter with Bill Clinton on the Phoenix airport tarmac:
The FBI ignored the Tsarnaev brothers before the Boston Marathon bombing.
The FBI ignored U.S. Army psychiatrist and jihadist Nidal Hasan before he murdered 31 people at Fort Hood.
The FBI ignored the San Bernardino terrorist killers Farook and Malik; then in an unforced fiasco bullied Apple for a needless unlocking key to the killers’ IPhone.
An FBI agent was actually following the Garland, Texas shooters without notifying local law enforcement that armed men were about to carry out a terrorist attack.
The FBI ignored Orlando nightclub massacre terrorist Omar Mateen, while under intermittent surveillance, whose lies to the FBI were known by the FBI interrogators.
The FBI has done zero investigation into who leaked classified info on Michael Flynn, nor the unmasking of more than a thousand private U.S. citizens, along with who spied on Trump and members of Congress.
The FBI has demurred in investigating the Clinton Foundation”
There is more at the link