This goes back to well before World War 2. Marxist professors came to the US - many from Germany. Some of the cleverer ones realized that the working class revolution wasn't going to happen in the US. The status quo had too many attractions, and the working class was pretty happy.
So they found other ways to divide the populace - by focusing on race, gender and sexuality. And, to challenge the status quo, they offered free sex and drugs (an easy sell anywhere). Sex does indeed sell.
They have been working for almost 100 years now to destroy the glue that holds society together, and are 95% of the way there. It can't be undone at this point. American is completely screwed. And there is no guarantee that they won't try to take everyone else down with them - probably through war.