And send the kids off to college, and take regular vacations, and all the other fantasies you see on those social media posts?
If nothing else, people had a lot fewer amenities then. Most houses were small (1 bathroom was not at all uncommon), many didn't have air conditioning, people bought and cooked their own food and never went out, there were no computers or smartphones or cable TV, clothes were hand-me-downs, Christmas and birthday gift-giving was sparse, and so on. The dollar went further because people were spending less.
And even with all that, middle class families survived, not thrived. When my mom (born 1954) was growing up, her family had two parents and three kids. Both parents worked (one as a teacher, one as a nurse), and the kids were expected to chip in money once they got jobs as teenagers. They entertained themselves in ways that didn't cost money, and still they were never rich. And that experience was not at all uncommon for the time.