I for a change am happy I had my kids in late 30s / 40. I am certainly wiser, way more experienced with world, humans, got to be successful and in much better financial position which also helped my parents to have better retirement.

I wasn't a full adult in my 20s, too naive, too trusting, undefined for the lack of better words, not experienced with various types of women (laugh all you want, this was probably the most important experience from all for me, it afterwards formed my choice of wife which is often the most important choice in one's life).

Plus I've managed in a decade before having kids to travel the world backpacking, various experiences that changed me for the better and basically reinvented myself, on my own. I don't come from competitive or nurturing environment, nobody expected anything from me. I've found my passions in various mountain/extreme sports. None of that would happen if I had kids earlier, thats very clear when looking at peers who took the other trajectory.

If my kids will have their kids young or older is completely up to them, I find it selfish to push any expectations on them, they (will) live vastly different life compared to me, I can just respect their choices and love them regardless.

I think your example of e.g. being able to provide a better retirement harken back to what times were like in the past. My parents and theirs on back had children quite young. It gave me a life where I was able to know my great grandparents. I didn't really appreciate it, or anything, at the time - but I hold those memories dearly now, in hindsight. And it also created an environment where social security, so to speak, was never any concern - you have about 20 relatives who are mostly all working together to make a better life for themselves, and always there for each other. Everybody was dirt poor, but you would never know it from what we were able to have.

If people start having children in their 40s then statistically grandparents will simply no longer be a thing, let alone great grandparents. And people's family sizes will substantially decline. I think that's quite sad from all perspectives, and also significantly detrimental. For instance there is so much I want to pass onto my children about having children (and I'm sure much I've yet to learn myself) but none of it will really 'stick' until they themselves have children. If they wait until their 40s then I'll most likely be dead by then.

And what we do we get in exchange in this sort of world? Slightly greater liberty to pursue self indulgence? And I think "slightly" is correct because you're right that self indulgences do become more difficult with children, but far from impossible, and even less difficult with large families. Want to head off to the mountains on the weekend? Sure, that's what grandparents are for!

> I was never especially fond of kids, but it turns I out love my own more than I imagined possible, and have more fun with them I ever thought I would!

That's because we're designed to have kids.