Seriously!
As a fully paid up member of the Historical Wargaming Master Race I am guilty on occasion of looking down my fine aquiline nose at the 40K crowd milling around below. Ok there are a lot of them, and tbh they can be a bit fragrant, but their games are "made up" and lack none of the authority and validation "our" games have, because we have HISTORY!! How can they compete with the vast span, scope depth and detail that historical games have? Space Pixies (or whatever) didn't exist. Winged Hussars, Persian Immortals, The Imperial Guard*, these all existed, Space Marines, not so much.
Except......................
40k does have a lot of background material. Since release in 1987 they have regularly updated rules and background, plus hundreds of Codex (army lists) novels and whatever. There is an awful lot of "stuff" built up over 33 years. I built a Dutch Marine force for Chain of Command and they fought for less than 6 days so there is probably more available info on Space Wolves than Dutch Marines. What I think I'm saying is there is now a depth of "lore" and info in 40K that probably outweighs the available info on something like Persian Immortals. OK the 40K info gets "retconned" regularly, but historical interpretation also changes - who remembers the Immortal figures from the 1980s with the viola shields and domed hats?
OK - it's not the same. But then again we should maybe recognise some 40k players spend a lot of time researching their armies just like the historical players do. There is more that connects us than sets us apart.
*Napoleon's, not the made up ones