If one were a Captain of a plane or a ship or a professional sports team or something and your name was say, for example, "Dan", I'm pretty sure you wouldn't need a personalized license plate to reaffirm your lofty hierarchical status. It fact it would be rather ego-deflating all those times in the navy compound when you're parked next to "General Steve". So, commuting into town in your truck with its vanity "CPTDAN" emblazoned license plate must then shout out "hey, look at me, I'm not a real Captain or anything but I encourage the kiddies to refer to me by this creepy, self-serving moniker!"
My apologies to "Dan" if, actually, what he does for a living is sell and install floor coverings and he's simply trying to be creative by drumming up interest in "Carpet Dan Inc."?!