In addition to things people have already commented on, the ability to obtain and maintain a security clearance also comes with requirements such as: being mindful and reporting things like contact with foreign nationals, reporting plans for and completed foreign travel, generally being able to account for your whereabouts during those travels to the day.

(Caveat: these are "rules" for regular people that have been given the privilege of holding a US national security clearance. There are many examples of people that have held security clearances that get away with conduct that would otherwise result in revocation and criminal charges for regular persons)