My eyes kind of roll every time someone says decadent society as it reminds me of communist propaganda.
Not seeing much of those four horsemen, either.
Do Russians not believe in things like equal pay, all jobs being open to women, fair divorce settlements, protection from physical abuse, access to family planning? (Honest question).
Likewise, equal pay sure, but dont you dare to point out when it is not. Naturally woman is the one expected to primart focus on kids and home, guy is more likely to be promoted of course. It is not seen as "not a woman place" to be leader - but it is happening less then incapable guy being promoted. Basically, there is more sexism but less hostility.
Jobs are not closed to women, but people perceive you weird putside of proper gender bounds and talk about it openly. The different expectations of boys and girls are in the open too. You wont find male teachers much, super rare.
Divorces seem fair money wise, except really guy will get less access to kids. But no alimony, she is expected to work. Access to familly planning is good.
Decadence as a concept makes a good polemic but it isn't a good source of judging problems let alone solving them. It really just means "I the self-proclaimed moral authority dislike this direction of society!".
The closest to an "objective decadence-like concept" is an expectation of a way of life that cannot be sustained without significant damage. Cottage industry after the dawn of industrializarion would be "decadent" as factory volume beats them out and can no longer sustain the middle class lifestyle. Not exactly what comes to mix when one thinks decadence but it is a lifestyle made unsustainable. There is no "sin" to it but it just doesn't work anymore and trying to force it wouldn't work out well. Notably even that is subjective and depends upon means. Having less than 10% of the population involved in food production would be stupidly unsustainable before agricultural advances but is the first world norm today.
It doesn't take much effort to find current instances of sword, famine, and plague. Only thing missing is the beasts, but maybe that's because we've already hunted them to extinction.
Then again, we've been seeing all four them regularly for over centuries...
And yet those things are affecting fewer people proportionally than at any time in recorded history.
I suppose any one unhappy with decadence, preferring spectacular instability to stability, a good fight against misfortune to contentment, and struggles with temptation or fatal overthrows by passion is free to become whatever flavour of jihadi they find congenial: https://news.ycombinator.com/item?id=24373042
David Crosby on how becoming a millionaire changed his life: "you know those pistachios that are hard to open? I don't bother with those anymore."