This is actually a common misconception. I don't have the reference handy, but I recently read/heard that in order for us to live with the same standard of living as people did in the late 1940's, most families would only have to work 8 months each year. This statistic was quoted for the "average" family, not the super rich.
As a family that lives on a single income, I know many people to "must" have two incomes to live. Some truly do but the vast majority don't. They'd have to give up some of the nicities of life, but they could easily and comfortably live on one income. I've seen stats on that somewhere, too, but don't have them handy.
We've been convinced by years of Democrat propaganda that most families NEED two incomes to survive. It's simply not the case.