Haha, i see this argument every time a player opt to play for a club in another league than the PL. Happened with Hakimi recently and Chelsea fans.Could be culture could be a lot of things , maybe he is more interested in the media side of things ? Much easier to build a folowing and an online presence in an easier league where your not having to keep on top of your game so hard as you would in the prem ? Not everyone who plays football loves the game per se .
I think you are a bit ethno centric. For many players, Real Madrid represent the pinnacle of the sport. After all, they are the leading recordman in European Cup/CL having done 3 in a row streak not too long ago. It is a lot more glamour being the new Real Galactico than playing in PL. Hazard who is a Chelsea legend was twerking every year for Real.
Also, remember that Mbappé was fan of Cristiano Ronaldo during his Real stint. He might want to walk in his idol path (won't beat the portuguese records nevertheless).
So not playing in PL doesn't mean opting for the easy life or not being a competitor.