The number instead of the letter is there just to get a unique username as wizard is usually already taken. So the remaining question is, why wizard?

A child mesmerized by technology and the mysteries it involved. Some incredibly advanced appliances available at home such as the VHS, the microwave oven or the Atari I had, gave me the opportunity to dwell into this world of magic.

Any sufficiently advanced technology is indistinguishable from magic.Arthur C. Clark

So after reading all the available manuals at home my parents already considered me like an expert on all those technology matters. For some time my parents took me to the houses of relatives and family friends to “fix” the annoying blinking displays of microwave ovens, passing the blessings of the knowledge on how to set the timer for TVs or clarifying the obscurity of camcorders menus. From there to my first PC, which showed I could be creating my own illusions through this witchcraft.

Witchcraft to the ignorant, … simple science to the learned.Leigh Brackett