Is it age or the rank of a Private that basically makes a Private seem arrogant?

I would say that the perceived arrogance has nothing to do with the rank or age/maturity. The boot camp/AIT/TechSchool process is designed to create the kind of self confidence that may be perceived as arrogance. For most recruits (of any service), accomplishing boot camp is the first difficult thing any of them has done. They are told they are the elite of the population, noble in their decision to serve, and accomplishing something as trying as basic training proves their mettle. They are then sent to learn their trade, but not just any trade THE BEST TRADE IN THE ARMED FORCES!!!, doesn't matter whether you are a cook, personnel specialist, infantry, or pencil pusher, ONLY the select few can do what you do. This is done to install a sense of pride in your career choice. So when that Private gets to his/her first unit thay may have an overinflated sense of self-worth. Usually gets corrected pretty quickly.

Good NCO's know not to burst that bubble, but to slowly deflate it to a point where all the egos fit in the room and work well togather....

PFC Shawn West Just wait! The E-4 Mafia gorges on people like you!

I address AIT students every month or so. They seem rather timid to me.