The point is to avoid that precise problem by parallelizing the child-having. My wife can only have one child at a time and medically recommended spacing is 18 months. The objective is to have our children as young as we can given our current ages.
We'll see where we get. In some sense, the revealed preference is that I didn't, considering I prioritized my career over finding a partner. But we'll see.
Raising children when you're old is so much harder, and you'll be mega-old when they're 20. I really don't see the point?