My impression is that the adults who have children and dislike them are outliers. Perhaps the children of such parents are disproportionately likely to grow up and write memoirs, producing the impression that you have.

Recognizing irony is not the strongest of your skills, isn't it?

No such thing as irony on the internet, you are the persona you choose to display.

Happy is overrated and fleeting, aim for a feel Ito for fulfilment instead.

Children are a fulfilling project.

I am happy everyday. It's far from fleeting. I don't have, nor am I going to have children. Maybe we understand "happiness" differently?

I was happy with no children, now I have a child I'm happy in a different way.

Sure there are days/weeks where nothing goes well, where you hear "I don't want you, I want mommy", but there are moments when you get the reverse, and even little things make you smile.

For example I was walking our child to daycare last week and had the following conversation:

   "Daddy, what plant that is?"
   "It's a rose"
   "It has spikes"
   "The spikes are called thorns, every rose has its thorn.."

So then I had to stop the walk, so I could pull out my phone and we could listen to the song. Moments like that are worth a lot of getting puked on.

Never had children? I'd have been happy, but I'm glad I did. Not everybody needs to, and the world would definitely be better place if relatives didn't ask every couple "When are you having children?", the moment they began living together, or got engaged.

I have a 2 year old and have a hard time accepting motherhood still. I am so happy in a different way but also so unhappy in another way. However before I had kids, I was happy but also unhappy in a different way because I wanted to get marry and have kids and wish I had them earlier. The more choices and opportunities life gives you (especially now with “you can do everything!” mentality) sometimes the more depressed you get.

Part of me has wished I'd started earlier too, but at the same time I think I appreciated my partner for a good few years, and I would have missed that time alone with them.

I guess having children changes so much, especially for the first few years, that there's no easy way to predict how anything will turn out. I've changed in the past few years, for sure. Though part of that is just natural growth, and a consequence of changing country, etc, too.