I imagine if you take the total cost of the the entire training organization including property and factoring in aircraft replacement costs etc by the number of pilots trained you'd get a figure something like that.
When I was training in the '80s they told us we owed the RN half a Million by the end of it.
Bear in mind that civvy training doesn't maintain multiple entire airfields plus gigantic offices in central London staffed by hundreds just to train a couple of dozen pilots per year...(OK - tongue in cheek figures, but you get the point)