No...they just want them for themselves. They want their fulfillment.
This is actually a good metaphor for a lot of things.
Henry Ford went into business for himself to make money. Selfish bastard. Now billions of people drive cars enabling them to work farther from home or travel to see family or whatever else they want to do.
Apple went into business for themselves. Very selfish of them. As a result, millions or billions or however many people get enjoyment from their products.
John and Kim want to have a kid. They do. The human race lives on.
When people pursue their own interests, it benefits everyone, provided you aren't using force against anyone.
Which is fortunate, because every action that people take is in pursuit of an effect that they themselves desire. Yes, that means all people are "selfish".
You eat because you want to satiate your hunger. You give a homeless guy five bucks because you feel good helping him. You tell your old lady you don't want to have kids because you don't. That's no less selfish than telling her you do. It is what it is. It's what you want.
And if you don't want to have kids, you shouldn't have to. It's perfectly fine. But the fact that other people have them doesn't make them selfish. Acting in pursuit of an effect that you desire is not selfish. It's being a living thing.
A better definition of selfishness might be concerning yourself with your own desires with no regard for the well being of others. This surely fits some parents, but not all or even most of them. And if they raise their kids that way, they'll fuck them up. But not everyone is as miserable as you think they should be, nor will there children be.