You need security clearance to get a clearance job. You need the job to get it though. Is that fair to rest of us?

That is not how it works.

And nothing is "fair" in real life.

don't know why it should affect anyone who is not applying for the security job

You don't need to have it to be considered for the job, just need to get it for working.

That's not how it goes. I work for the government. I have a security clearance. When I was hired, I was hired right out of college. I had no security clearance and no prior work experience other than flipping burgers in high school and driving pizzas in college. Getting my security clearance required the FBI to do a full background check on me, which was no small affair and included me filling out a questionnaire that was about 40 pages long that basically gave my life story back to birth and not just sign it under penalty of perjury but actually raise my hand in front of an LSO and swear to it, passing a polygraph, and passing a drug test. After doing that, it took the FBI about 60 days to complete its investigation. I know they were thorough because several people were contacted by the FBI about me, like a former pastor I hadn't spoken to in years, my high school principle, and my college roommate freshman and sophomore year whom I was and still am friends with, but I got my security clearance and was hired without having had a security clearance before or even a job that handled anything more sensitive than pepperonis.

Your job requires a clearance, you go through that process at the time of hire, You don't qualify for a needed clearance you are done as in terminated.

Took me 90 days to get my top secret clearance during probationary on the job.