How is the Imperial nobility managing to protect themselves from Slaanesh?

Every story I’ve read and near every piece of fiction involving 40k and the Imperium as a whole again and again has moments harping on about the nobility, aristocrats, planetary governors, the rich well connected few.

Yet a part of me can’t fathom how they all haven’t just fallen to Slaanesh and destroyed the whole damn Imperium.

These guys are a bunch of incompetent spoiled children who have all the money and luxuries in the world and are very often portrayed as the most decadent complacent people around who look like they’d be easy steals for Slaanesh.

Yet the Imperium functions, there’s plenty of non-corrupted nobles and high ranking folks, how? These sorts of people seem like they’d be in such abundant supply that Slaanesh alone could topple the IOM in a day.