The Air Force has too many people cleared for access to the highest classification level. The clearances require more frequent re-investigation and at greater depth than a secret clearance, and very few people ever access Top Secret material.
For example: every pilot is investigated and cleared for Top Secret access during pilot training, even though only a tiny number of those pilots will end up flying aircraft that require Top Secret access. Investigations for these clearances are more extensive, more expensive, and investigations to keep them current are twice as frequent as those required for Secret clearances. In my unit, I was able to cut the number of required Top Secret clearances by more than half, at an estimated savings of $12K per year. My base has a security office manned by several GS employees whose entire function it is to process these clearances. Cutting them in half would also permit a commensurate halving of the supporting administrative labor force. Multiply this model across the Air Force and you're talking millions of dollars per year in savings.
There will be resistance; this bureaucratized process exists at great interest to many firms, contractors, and employees. But the immutable fact is that the Air Force has far more people cleared to access Top Secret material than require such a clearance.