You have 1/2 the picture, the other 1/2 is economics.
It’s hard to have kids when your broke, unless someone else is paying for you kids and you don’t mind.
The last 30 years have been very hard on MC/Working American’s. Many aren’t financially able to have families until their 30’s
Of course for many people your explaination is correct not economics.
Many don't seek out difficult, well-paying jobs, but are content working for teenager wages. There are plenty of jobs a man could raise a family on, but you have to work long hard hours at physically and/or mentally challenging work.