That's a very difficult question to answer. There are a lot of different factors that go into it. Some people aren't willing to sacrifice their own happiness for their children's happiness. Some people are moving away from religion and the concept of marriage. Some people are having kids as a way to maximize what they can receive from welfare.Why do you think this is?
Statistics show that there's a significant correlation between single parent households and things like: test scores, income levels, crime rates, & incarceration rates. People talk all the time about different types of privilege. The biggest privilege someone can have in life is being born into a family that will care for them and teach them the things they need to know to be successful in life.