Or put differently, few of the fairly wealthy non-home-owners buy homes (which would bring the gap down from four thousand per cent). That's odd, isn't it? Why not?
I can manufacture a netw orth of average Anerican homeowner with a bit of paperwork. Legal fictions are wonderful things. Statistically invisible if you aren't combing the right datasets.
I reiterate: The median-measure makes that irrelevant.
Sure, perhaps someone like Jeff Bezos might spend a million to employ a crack-squad of devious mercenary accountant-lawyers to disguise his apparent net-worth... But shifting from a top-1% "homeowner" down to top-10%, or top-20%, or even top-49.999%? That has zero effect on the final result.
In other words, the kind of people with a motive+capability to hide their net-worth are very unlikely to ever disguise it all the way down to <=$400k, and the people who are truly at <$400k simply don't have enough motive+capability to try the same tricks.