Brennan and pals still have influence inside agencies to steer government contracts to the likes of Booz, Alexander, Hamilton. Loosing the clearance will cut him off from all classified info/$ kickbacks.
And we, the taxpayers, would have the privilege of renewing their clearances every 5 years. Brennan’s muzzy so he’s afraid of not getting classified into to America’s enemies. Same with Hellary. Same with the rest.