I suspect a lot of the "woe, things are way harder for Millennials than past generations, I'm too poor to have a family" zeitgeist is actually this phenomena + literal survivorship bias. Every single person alive today came from parents that successfully reproduced. When you're a kid, it's very natural to think that having kids and a family of your own is the default state of being. After all, all of your friends have parents who successfully reproduced too.
But that's because you tend to have much closer relationships with your family and peers than with childless adults. When I change my sample from "my friends growing up" to "my parent's friends when they were growing up", a lot of them never had children. By the numbers, the percentage of households that are families with children has gone down, but it's gone from about 55% in 1970 to 40% in 2022, which is a much less drastic fall than most people would suspect. Being childless is far more normal than children believe.
You raise an interesting point, but you also seem to be conflating two things. Having children is more expensive than ever, and purchasing power has continued to drop for decades. Not to mention the drastic increase in specific "raising a family" essentials/barriers like housing costs, medical debt, educational debt, and childcare expenses. I don't have numbers to back this up, but my intuition (based on observation and casual reading) is that more working class people who actively want to have children are not doing so because they are stretched too thin than we saw in the 1970's (when people could work part-time to pay for all 4 years of college and expect a high paying career out of their degree).
Also, a 15% drop in 50 years is nothing to scoff at. In America, we are below the replacement fertility rate of 2.1 children per woman. Currently it is at 1.7, so our population would be declining without immigration. [1] This is not a bad thing in my opinion, but it is extremely significant in terms of politics, culture, and economics. If our fertility rate continues to drop expect to start hearing about it more often and at higher volume from many different corners.
Why would any of that be specific to millennials, though? The way you’re describing it nothing would have changed in a very long time.
I’m pretty sure the “I’m too poor to have a family” perspective stems directly from the wild increases we’ve see in the price of housing and not a whole lot else.
That's the point - nothing has changed, except the narrative.
The wild increases in the price of housing is a symptom of the same dynamic we've seen throughout time, of competition over resources and survival of the "fittest" (where "fittest" occasionally means most brutal/devious/selfish). The differences are that a.) The (white) Baby-boom generation (in the U.S.) bucked the trend and enjoyed abundance and very little selection pressure. Note that the story was very different if you were black (where you had the gains of the Civil Rights movement, only to have the rug pulled out from under you with the 70s inflation and 80s crack epidemic) or if you were Chinese (where you probably died in the Cultural Revolution or Great Famine) or Russian / Eastern European (where you likely drank yourself to death after the breakup of the Warsaw Pact). And b.) that in our "civilized" society, we prefer to let people die rather than kill them outright. Not so for the WW1/WW2 generation.
But that's because you tend to have much closer relationships with your family and peers than with childless adults. When I change my sample from "my friends growing up" to "my parent's friends when they were growing up", a lot of them never had children. By the numbers, the percentage of households that are families with children has gone down, but it's gone from about 55% in 1970 to 40% in 2022, which is a much less drastic fall than most people would suspect. Being childless is far more normal than children believe.