The ultra wealthy alone basically live in debt. They use debt for everything. That’s one reason they pay virtually no taxes. That would skew an “average”.
Also, mortgages and auto loans would make this way higher for average people.
OP gets the number for the post from here I suspect
Simply dividing the amount of debt by the number of people does things like decrease the debt per person if there are children in the house.
There are other weird scenarios like non married people who own a house together. When you purchase a house with someone both parties are responsible for the debt, so 100% of the balance shows up on both their credit reports.
There may be some broad trends that can be gathered from this? If anybody has any idea what they are I'd be interested in hearing. Right now I can't think of any