Settling down and starting a family is a boring, long term endeavor that doesn’t really play well in most media formats. Therefore it just doesn’t get any space. The protagonists of basically every TV show do not have families. And that’s because it wouldn’t be feasible for them to do all the stuff that makes the plot interesting if they were tied down by a family. And people are getting cues about how their personal story arc should play out from the media they consume.

But you’re right that capitalism is excellent at providing the means to life a life of self involved, hedonistic excess.

the chemical environment people grow up in today is different from the one 10 years ago, or 30 years ago, etc.

we may very be improving in some dimensions -- like removing lead -- while getting far worse in others (plastic and anti-androgens).

We don't know the cause, but environmental hormonal causes are one hypothesis.

Here's one aspect: https://en.m.wikipedia.org/wiki/Testicular_dysgenesis_syndro...

It's easy to see how lower testosterone would lead to less sex. It is very unlikely to be the only cause, but it likely has some impact.