Decadent mass culture, in a sense has three variants,

>the 1890s, an upper-class version of it.
>the 1920s, a bourgeois version of it.
>a blow-out period after the excesses and privations of the Great War and thereafter.

This all reached a crescendo at/around the 1960s when these mass counter-cultural energies all simultaneously became bourgeois in orientation while also becoming proletarianized.