Are you talking about short time scales, or periods of years?
We had students who used their time to study, some read books, others used their beats for exercise, and some just plainly enjoyed a job that was stress free ninety nine percent and more of the time.
At first when I worked there, coding a wide range of programs including payroll, I was a bit distressed at the pay scales. However after meeting many different guards I came to realize that many saw advantages I didn't and they could not understand why I wanted to work so hard, all day and sometimes more at a computer.
They're not making engineering salaries, but for a job which, let's face it, requires no skills or education, the make a very decent rate.
Add in a personality which loves a little power and being a TSA jockey surely looks pretty good.