In other words human society is reverting to the way it always has been since the dawn of the agricultural age 12,000 years ago.
There was never any reason to believe that the monogamous system of the 1950s West was a permanent stable arrangement and indeed we are seeing its death in our own lifetimes.
It's not exclusively a "West" thing, and it never was. Monogamy has been a stable and thriving system in many parts of the world for centuries, well before the 1950s or the Western framing of it. Societies in South Asia, East Asia, and the Middle East, for example, have long upheld monogamous traditions through cultural and religious practices, sometimes even more rigidly than the West.
Newton was a genius with an amazing model, until Einstein showed he was thinking too small, and its becoming apparent that Einstein missed something at this point. Humanity advances by pushing and testing limits.
Your "1%" will just go to clubs or on Tinder and hook up with other conventionally attractive people, without having to deal with some weirdo subculture.
Pretty much. There's a lot of swingers these days, but no one with a triple digit IQ will raise their say "Hey I'm a swinger!" to their entire friend circle due to all the downsides that come along with it. People just do it quietly to avoid causing drama (from usually ugly people). I've always suspected the need for people to declare these types of alternate-sexuality lifestyles is more attention seeking and validation than actual organic expression of an identity. The loudest ones about these lifestyles are usually the most boner-killer types in terms of looks.