I think the point is that the decisions aren't as high-risk when you are single and don't have other people to support (especially children). The consequences of failure aren't as high.

Instead of being able to share a place with a few people (maybe even sharing a room) and sharing utilities, internet, cable and so on, you are paying significantly more for housing, food, utilities, transportation (bigger car), clothes and insurance/medical costs. Those costs could easily be 3-4 times as much as a single person.

If you are a dual income family, you may also be paying for child care and have the extra responsibilities of getting your children to and from child care and/or school (let alone actually spending some quality time with them). Working late has a much higher cost and being out of a job has much greater consequences.