Earlier quoted context omitted.
>Most developed countries are already worried about declining birth rates Yes, because of housing, healthcare, childcare and education costs spiraling out of control and the difficulty of getting well paying jobs to cover those costs are pushing youngsters to spend their youth and most fertile years hunched behind a desk studying and working to climb the corporate ladder to afford a home bigger than a shoebox in the…
I'm sure they play a role, but I have read that even teenagers are having less sex. I don't think teenagers are thinking about housing and childcare when not pursuing sex.
To your point, there are multiple reasons causing people to have less sex and less children.