I concur except about the bureaucratic administrators. I think they do this because the upper class will replace them if they don't do the work of asserting the upper class's power.
The upper class doesn’t need dress code. They know they are the upper class. Dress codes are for petit bourgeois and the upper middle class who try to pretend but everyone knows they are actually middle class.
The billionaire they were working for wore stuff that was expensive, old and hence comfortable. He didn't have to play to anyone.
He did dress up to meet the president though, he had to play a part.
The president has to dress well all the time, he is always playing a part, in front of the whole world.
Wear your part. Or don't, if you don't want any part in all of this (which seems to be Magnus's motivation, or lack of it).