Why did 'Jihadi John' flee Islamic State?

British terrorist 'Jihadi John,' one of the most well-known members of ISIS, has reportedly fled the terrorist group, fearing for his life.

British terrorist “Jihadi John” has reportedly left the Islamic State (aka ISIS) group, fearing for his life after being identified six months earlier as a Kuwaiti-born Londoner from a well-to-do family.

Jihadi John left because the terrorist organization might drop him "like a stone or worse if they feel he is no longer of any use to them," according to a source for the British news outlet, the Daily Express.
The Daily Express report has not been confirmed by government sources or other news outlets.
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Born Mohammed Emwazi, he initially gained international notoriety both personally, and for the terrorist organization, after a video was released by Islamic State in August 2014, showing him beheading American journalist James Foley.
"We have never been prouder of our son Jim," Diane Foley wrote on her son’s Facebook page who was killed after two years in captivity. "He gave his life trying to expose the world to the suffering of the Syrian people."
Mr. Emwazi is now wanted for murder by the United States and Britain for killings journalists and aid workers Foley, Stephen Sotloff, David Haines, Alan Henning, and Peter Kassig, among others. The last video that the Kuwaiti-born 26-year-old was featured in depicted the beheading of Japanese journalist Kenji Goto over six months ago. The Daily Express speculates that Emwazi may be working with "a less well-known jihadist group somewhere in Syria, to try to keep a low profile."
In February, The Washington Post unmasked the hooded terrorist, reporting that Emwazi grew up in West London in a prosperous family, and graduated with a degree in computer science from the University of Westminster. Conflicting accounts regarding Emwazi’s behavior in high school and college have sprung up, ranging from descriptions of a well-behaved student of Islam, to one who flouted authority and Muslim behavioral codes for drinking and drugs.
WHEN DID HE RADICALIZE?
The young man attempted to travel to Tanzania following graduation from Westminster, but was detained en route. Security officials questioned whether the young man was interested in reaching Somalia to locate terrorist groups in the North. Years later Emwazi moved to Kuwait, and was detained on multiple occasions when he returned to London; at one point he was directly prevented from returning to his native country of Kuwait by British authorities.
“I feel like a prisoner, only not in a cage, in London. A person imprisoned & controlled by security service men, stopping me from living my new life in my birthplace & country, Kuwait,” he wrote in an email to a friend. It is uncertain how Emwazi left London and returned to the Middle East.
IF HE LEFT, WHAT DOES EMWAZI'S DEPARTURE SAY ABOUT ISIS?
Emwazi reportedly fears that his value as a member of Islamic State has been reduced now that the public is aware of his identify. Despite gaining substantial media attention and coverage, ISIS still operates largely in the shadows. Even the leader, Abu Bakr al-Baghdadi, is a "relatively unknown and enigmatic figure," with an unconfirmed history, according to The Washington Post.
The militant group “excels” at recruiting youth through appealing to a sense of identity, sophisticated Internet propaganda, appealing to the sense of religious obligation, and female-targeted recruitment, according to a report from The Christian Science Monitor.
Last year, the CIA estimated the number of members of the group to be upwards of 20,000, as reported by NPR. While the departure of a single member might not make much of a dent in the group numerically, the loss of Jihad John, one of the highest profile members of the organization to the outside world, may indicate some turmoil within the organization.
Mr. Baghdadi announced a week ago that IS would no longer show scenes of the actual executions in the gory beheading videos the group (and Jihadi John) has become known for.
Christian Science Monitor.