The laws say differently. Once you impregnate her and have kids, the woman gains the power and can take 50% (or more) of your money from you via divorce court.
Financially speaking, having kids and getting married is the worst thing a man can do to harm himself. I guess there are a lot of masochists out there.
Prenups in the US.
A prenuptial agreement, antenuptial agreement, or premarital agreement, commonly abbreviated to prenup or prenupt, is a contract entered into prior to marriage, civil union or any other agreement prior to the main agreement by the people intending to marry or contract with each other. The content of a prenuptial agreement can vary widely, but commonly includes provisions for division of property and spousal support in the event of divorce or breakup of marriage.