Dude, background checks are brutal. You can be denied because your parents (not you) struggled to pay taxes. You could have acedemic dishonesty that disqualifies you (that one small area where "permanent record" in school may actually cost you something). There are so many little things that no other kind of high paying job cares about in background checks that are suddenly red flags for clearance.
There's a reason Musk especially kept dodging trying to get proper clearance. He isn't even fully cleared to see all aspects of SpaceX. Some of his employees he brought in probably aren't better off.
