In Germany a person with median income will have access to free healthcare and education, good public transportation system and maybe even to an apartment with controlled rent. After you subtract all those expenses you may find that people in Germany may have more money in the pocket than in the USA. Anecdotal evidence does not prove anything, but few Americans who moved to Berlin were actually telling me that despite lower income and higher taxes they have more money here.

You're looking at the mean which includes billionaire disposable income. Look at the median for a more realistic picture (scroll down 1 grid).

I doubt many billionaires have income. Although you're partially right, I'm not sure which is a better metric. Probably depends on where in the distribution you are (above or below the median).

>I doubt many billionaires have income.

Realized capital gains, dividend income, income on rents. I'm not sure how the calculate disposable income. If I have 200M in stock that I could sell, is that considered disposable income? If I earn 2M in dividends that I reinvest, is that considered disposable?

for this exercise, I'd consider 'loans against equity' to be disposable income.