It's been brought up multiple times before, but Warmachine and Hordes from Privateer Press was actually outselling 40k for a couple quarters(alongside x-wing) back in around 2013-14 or so. Privateer press had been around for over a decade at that point, originally making D&D campaigns based on their own setting. So they had a setting, understood world building, then pivoted to miniatures a couple of years after that, and built themselves up a fanbase and everything. They even had the benefit of people being fed up with 6-7th edition 40k. And once they were successful, shot themselves in the foot, pissed off 80% of their fanbase with mk3, mismanagement of the company, and so on. It's been posted repeatedly before, no need to bother with a bunch of detail.