Oh, the Rentiers
In Europe and parts a bit to the west, the rentiers were severely damaged-- more so in WWII than in WWI, as WWII saw more worldwide damage.
The rentiers are the ones who (besides living on the stored assets and the sweat of others to a large extent) also mostly want the status quo in order to maintain their positions-- any changes had to be "positive" (like a reduction in income taxes at the top end).
The wars upended the financial and social stratification-- vast wealth and ossified economic empires burned to ashes; lots of niches opened up for people to move into from the oppressed masses below.
Eventually all that cruft regrew, more rentiers established their financial castles, and here we are again. Unfortunately, a new world war probably will open rather more niches in society than one may want...