Do you think I should tell my friend that he's not ready to have a baby?
Why do you think your friend's not ready for a baby?
He's very irresponsible and I don't think he can take care of a child.
You should find a way to share your opinion with him. It will hurt his feelings so be careful how you tell him. Try to get him to reconsider taking on a responsibility like this.
It will be difficult, sometimes he doesn't want to listen to reason.
Convincing your friend he's not ready for children won't be easy but it's for his own good. Keep trying before he makes a mistake that he can't easily fix. Children are a lot of responsibility.