I’m no expert on this, but it seems to me that high taxes play a part. Back in the 1950s dad went to work while mom stayed home and raised the kids. And it didn’t matter much if dad was white collar or blue collar. His salary alone was sufficient.
Now both parents work. Sure, maybe they’re greedy for expensive toys. But also maybe taxes are taking too big a bite out of dad’s salary.
There are so many other reasons why the birthrate it low including easy access to contraception and abortion, women not wanting to marry men who make less than them, women waiting too long to have babies, social media and dating apps ruining couple formation, bad/uncertain economy leading couples to be too afraid to have kids they fear they won't be able to properly support, etc.