This line of thinking actually makes sense if you look at it from a different perspective. What they are saying is sex doesn't matter because it is such a normal part of their lives. It's like eating or drinking. To people living in well off countries, we could say that food doesn't really matter because we have enough of it and we don't think to much about it going about our lives. But for someone struggling to get food, food is constantly on their minds. Or a better analogy, a billionaire would say that money doesn't matter because money hardly ever crosses his mind. He can buy whatever he wants. If you see someone struggling with money, money matters a lot more to them than the billionaire.