I'd also tend to argue the top 10% skew that number greatly as well. Just b/c you "go to college" and "get a degree" doesn't really mean you're earnings are related to the degree. Generational wealth probably has a great deal more to do with those numbers than a degree or lack thereof.
They skew that average maybe a few thousand dollars averaged across everyone who has gotten a degree (approx. 30+% or around 100 million people). That's a lot, but it doesn't skew it as much as it would seem.