What is the perfect number of children to have?

In my opinion, having two of children is the best. 

=> Corrected : The sentence is corrected grammatically. 

We need about hundred thousand dollars to raise one child until he becomes an adult. ​

It is quite expensive. ​

What's more, we need to prepare our lives after quitting our jobs. ​

So to live a satisfied and comfortable life, people recommend that we should raise the only one child. ​

However, if he is the only child in the family, it could be difficult for the child to get along with his friends or to care for others well. ​

I want my child to grow like a man who is very considerate. ​

To stop him from being selfish, I let him have a friend, his sibling. ​​