I have 13 cousins. My two kids have 2.
When I ask my cousins and siblings why they don't want to have the kids the opinions range from too much of a restriction to my freedoms, too expensive, too much work, it'll ruin my body.
These area all valid reasons and in fact it was a tough sell for my wife and I to convince ourselves whether even we should have children. I'm glad I did, but I had no idea how much work it takes and I honestly would not judge anyone who opts-out of having them - but...it does mean we face demographic collapse and free child care is just not enough.
Give young families cheaper homes, cheaper college education and have a cultural shift which values having a child as much as a career if not more so and maybe we'll start to see things change.