Oh, heavens no. But I'm self aware enough (and socially well adjusted enough) to have a decent idea of what is and isn't normal, and I don't pretend that my abnormal behaviors are in fact normal.

People have used pen names all the time.

Look at you, HideousKojima. What's your real name? Why do you pretend to be this online alias? Is it normal to hide your identity and interact as if you were someone else?

It's generally considered poor form to have a pseudonymous alias that interacts with your "real" account while pretending to be a separate person.