The "non-existent" Kingdom certainly did not exist back in 1914/1918 or whatever. It took Rutherford until 1929 to "rewrite" doctrine to his own suiting before the THEOCRATIC KINGDOM was seen to have been established during those years. Indeed, Rutherfod did have an imagination to come up with his silly ideas of creative Biblical interpretation. Despite being a lawyer and a "Judge", he did not understand what the words "evidence" and "proof" really meant.
Basically, the doctrines concerning "non-existent" things are merely wishful thinking along with some circular reasoning thrown to give justification for the existence of The Watchtower and its authority over its followers.
It is the man-made efforts of The Watchtower organization (or business!) that accomplishes the "bringing in" work!