The combination of median disposable income and housing wealth being at all time highs is a big part of it!

Those with housing have locked others out of housing, causing lots of "wealth" that those with housing don't even consider to be wealth. They think it's just "normal" and don't realize the massive advantage it gives them over everybody stuck renting.

But that's symptomatic of all the other inequality. Housing is the biggest expense, and most obvious form of rent extraction that the wealthy use to exploit those without wealth, but it's not the only one.