I think the "it's too expensive" part is a very minor part of the issue.
People had way less opportunities one or two generations ago, and my parents generation in Italy bought their house with a mortgage and payed it in decades just like their kids did.
What changed is expectations: you feel like you should travel before getting a kid. You should have plenty of sexual experiences before picking a partner. You should give priority to your career before settling in a given city, etc.
Empowerment of women made "get married and out of your parents house" a less interesting option, education and options for people added up, and cultural shifts happened.
Having children is just another bucket list item these days.
People had way less opportunities one or two generations ago, and my parents generation in Italy bought their house with a mortgage and payed it in decades just like their kids did.
What changed is expectations: you feel like you should travel before getting a kid. You should have plenty of sexual experiences before picking a partner. You should give priority to your career before settling in a given city, etc.
Empowerment of women made "get married and out of your parents house" a less interesting option, education and options for people added up, and cultural shifts happened.
Having children is just another bucket list item these days.