Discretionary income, really, not disposable. What we really should care about is the cash people have left over after they've paid for all their essentials, not just what's left over after taxes.

It might seem like it would sound impressive to say that someone has $20k/month of disposable income, but not so much if the housing market has gone crazy and groceries have become scarce and they have to spend $15k/month on a small apartment and barely enough food to feed themselves.