It's not an ego thing...I swear...
I used to be a teacher. In NYC, I used to hang out at this great little pub, where everyone knew my name. The owner's wife, during a late night conversation, decided that my new career path in education warranted a new moniker, and a few hundred sips later, The Professor was born. After this, rather than people learning my real name, most just called me "Prof" while never bothering to ask why.
My days of teaching are over, as I've returned to being the desk jockey (and on-time bill payer) I always knew I could be. However, despite the fact that I no longer come home covered in chalk and mystery rashes, this alias is as much a part of my identity as the name my own mother gave me. And it isn't going anywhere...
Maybe it is a bit of an ego thing, after all...
