I put the genuine peak of western society around the 1400s just before the Protestant revolution, everything has more or less been downhill for there at a civilizational scale, with brief periods of relative recovery and stability that got increasingly short.

I place the point of true decline at the French Revolution though, and the end of that struggle were the world wars, after that the decline seems to have fully picked up with the world dividing into Eastern tyranny in the molds of “1984” and Western hedonism in the mold of “Brave new world” and now the two are getting mixed into the most gay and generic “Cyberpunk dystopia” possible.