As with most things Vox, it's largely correct but simplistic. At the very, very end it gets to the amount of money left over, rather than it being the principal problem. Their graph of deciles were tax rates, not overall wealth. In the US, the bottom decile makes less than $10,500. The top decile makes more than $184,900. The bottom decile pays an overall tax rate of 27%, the top decile pays an overall tax rate of 29%.
So. The bottom decile has $7600 a year to live on while the top decile has $135k. Average cost of living is, of course, a highly contentious number, but let's go with these guys 'cuz we gotta go with sumpin' so... $20,194 per person per year.
The bottom decile is a factor of three away from hitting the average cost of living - three people in the bottom decile could roll all their earnings together and one of them can pay the average. The top decile can almost but not quite pay the cost of living for seven people.
Let's say we add the cost of living of one American to the taxes of the top two deciles - all of a sudden, the bottom decile can live with dignity and the top decile still has $110k to live off of.