Otaku (おた) is also a formal way of saying "you". た means "house", and with the honorific お, it literally means "your honorable house", implying that you are less of a person and more of a place, fixed in space and contained under a roof. Makes sense that the stereotype of the modern otaku is a shut-in, an obsessed loner and social isolate who rarely leaves his house.
Ruth Ozeki, A Tale for the Time Being
japanese, language, otaku