These statistics all measure the wrong things.
Let me tell you a story of two families. My step-dad was thrust into a parenting role over his siblings, a sister and a brother at an early age. The brother died early, in a train accident. My step-dad married my mother and they're still together, over 20 years later. His sister is on her second marriage.
My aunt's family is constantly teetering on the edge of poverty, having obliterated their family's nest egg over decades of stupid decisions. Our family clawed our way out of low class through pragmatic saving.
Stupid decisions are what make the difference between affluence and poverty in the US. You can have all the money in the world and still be broke. The capacity to make stupid decisions largely comes from childhood. It's the emotional makeup of a household that mostly determines what children are like when they get older. If you grow up in America feeling neglected and abused, you're going to go through strings of bad relationships and that's just going to be your life.
I call America's brand of poverty "emotional poverty." Food on the table, roof over your head, cable TV and video games for entertainment, all things people in other parts of the world can't reliably have, in the US pretty much come out of the tap like water. Even homeless people here have cell phones.
No, what's missing here is emotional warmth. People in the US just can't figure out for some reason how to treat each other well. They eat, but they don't live.
If you're lucky enough to avoid emotional poverty, then you can join America's middle class. If not, you'll fritter away all the money you ever make. It's got nothing to do with how much money your family has and everything to do with how they treat each other.
No statistic could possibly capture this reality.