A lot of this is just a wealthier society with more people in professions with a longer runway. (My father wasn’t married, employed, and a father until 33, and I was 36. Not really that different, and in neither case was the rate-limiting step money.)
Indeed, rare I disagree with @cremieuxrecueil (whose broader point is good) but I propose the right metric is
“What share of men at 30 are married, employed, fathers?”
A drop of ~50% → ~25% in one generation