Why does 40K remain THE wargame?

After decades, 40K remains so dominant in the table to wargame sphere. But why? Is it because of the whims of the market? Because of the lore? Or because of the game itself?

Personally I think it’s the lore, along with the game being sufficiently deep with dozens of factions. Along with the quality of the miniatures themselves. Personally I was well versed in 40K lore well before I started buying and painting minis.

But there’s loads of other war games out there, and some with deep lore behind them, like Star Wars legion. Historicals are a bit of a league of their own.

I’m curious what other 40K fans cite as the reason why the game has endured and dominated as long as it has.