I'm pretty close to OP's age, I'm not a millennial by any stretch. I couldn't fathom it either. I had kids when I was ready, not two years after I graduated from high school. I partied, traveled, and spent extravagantly, and it's all seems so meaningless to me now. What did any of that ever get me?
No one is saying have a kid with your next erection, but how long do you want to be the old guy pretending he's not?
So you have to have a kid to be a grown up?
Not every childless person is doing coke off stripper titties in their 40s.
I am undecided on kids. My gf and I are both up for it physically, financially and emotionally, but I can easily picture the next 6 decades being very relaxing and enjoyable without creating a life that the world probably doesn't need. Might just get a second dog and call it a day.
I think it's very easy to become absorbed when you have young children. My youngest is now 14 and I certainly don't feel that way now. Not sure if I ever did really to the extent that you quoted.
Kids are great. They're your family and they're easy to love because they are essentially obsessed with you as a parent. At least in their younger years. It is easy to think or care about little else. But it is also easy to enjoy and conintue to learn about new things and experiences because you are introducing the world to your children as they grow.
Finally someone sensible.