Why do people that don’t have kids talk to the most shit about people with them?

A girl that I went to school with posted yesterday about how single mothers need to stop patting themselves on the back for doing their job raising their kids. How kids need two parents and we should be more careful who we let impregnate us. Then a couple hours later she shared a photo of what apparently happens if you give pacifiers to your kids ( my kids teeth are fine) but she was saying how parents shouldn’t use them