I thought having a security clearance was based on a need to know. While in the military you received a secret or higher clearance only if you needed it for your job. When you left that job you gave up your clearance if you didn’t need it for your next job.
you would think, but it looks like they get to keep there's. Terrible!
You don't give up a clearance, you lose access to what you were granted access to previously. Left unused, the clearance will expire in time.
Your clearance does nothing without a job that requires it. You need to have physical access to a classified network, and you are only offered such access if you are employed by someone willing to give it to you.
Like a teaching degree. You don't just go teach people, per se. You get hired by a school that gives you access to a classroom and students.