This sounds more like an anecdote of “my brother-in-law and his friends are losers” more than any indication of a trend.

The median income almost doubles between age 23 and 35.

There's definitely a transition associated with becoming a parent - that is well documented.

When I think about my friends and friends of my relatives, what GP described appears to be the norm - also among the educated and in the upper-middle class. They often identify themselves as "dog parents".