Housing prices are 9x salary vs 4.5x salary in the 70s and it takes a while to save up. Personal data point: it took me winning an IPO lottery to start thinking about having kids for real. Having kids while earning minimal wage? Terrifying, especially in the US where getting yourself or your kid sick could bankrupt you in the blink of an eye - and if you want multiple kids you increase the risk.
So we think we have to have it all before we start trying having kids and have no sense of community whatsoever. Societal focus on hedonism and career leaves little to no time to raise kids. And at the end of the day you end up having no support from the society that slowly but surely ages.