>>96439367
That's all common fan lore but it's all bs.
In reality GW only lost money during the 4th 40k era due to a mix of factors. And the current boom began with the AoS GHB and 8th 40k featuring new marines (after everybody was tired of the now "classic" manlets)

And 40k 8th+ is not like D&D 5e at all. While in both cases thye got a lot of new players, in 40ks case actual active players remained while adding many old guys coming back from their teenage years, not just noobs.