Our two boys. Matyáš on the left. Almost five months old. Nikolas on the right. Almost three years old.
I can't explain why anyone would want to have a kid, but I know why you should have a second. The first one instantly grows up.
As my wife grew fuller and rounder, I told Nikolas how his life was changing. He no longer would get all his mommy's time. Not even the big half. But he would gain a buddy and experience the joy of helping him grow up.
He had his jealous streak early. Pre-partum. He clung to his mommy and wouldn't let me change his pajamas or do anything if she was around to do it.
I gave him the title "Assistant Birth Coach". He performed admirably: bringing her food, cleaning up and getting his brother's room ready.
Upon Matyáš' birth, Nikolas dropped the clinginess almost completely. He's been a great big brother. Instantly more independent. Enjoying nights out with daddy. Helping his little brother as much as possible. However, I do have to ask him to stop kissing him so much.
I'm the youngest of three, so I don't know, but I suspect only-children never have to make this change. Nikolas knows he's not a baby anymore and is looking upward.
And in case you're curious, that's Mah-tee-ahsh. A Czech version of Matthias or Matias.