Should a dad have to pay for child support when he takes his son?

Why should you get child support when you don't have the child? The point of child support is to help with the costs of raising a child. My daughter doesn't even cost me $300 a month so it sounds to me like you get plenty of money when you have your son. Sounds to me like your just in it for the money...sad. Why don't you pay him support for the months he has the child?