That's only relevant when everyone is able to buy a second car, though. Inequality is currently so extreme that some people cannot even afford to go to doctors, dentists, or even to not be homeless. While some people die homeless, we have people that worry about whether they can afford to buy the right kind of island for themselves.
Currently, the upper class just trade money between themselves as the majority of profits goes to the top. What enriches everyone is when consumers on the lowest end spend their money to smaller businesses, creating demand that further create more incentives to supply goods.
When a few corporations own most of the economy, with the profit going to the rich for them to send money between themselves, then the majority of that money will continue to stagnate at the very top... without helping the economy. They won't help society.
Here's a relevant example, "On average, 48 percent of each purchase at local independent businesses was recirculated locally, compared to less than 14 percent of purchases at chain stores." http://www.economicsonline.co.uk/Managing_the_economy/The_multiplier_effect.html
If all the businesses that exist in a country are replaced with chain stores, then local economy will fall apart. That's what happens with extreme inequality in our current system.
I could write "when one person is able to buy another piece of cheese, another will buy a new car" (in my childhood I was grown up in a family where another piece of cheese was a problem).
But that's why I understand the great motivation of a person to have money when you really do not. Money should not be granted because we still need other people doing service for us. We cannot afford to get rid of humans now in the hospitals, in the restaurants and so on. I need doctors and I know that we will have at best 1000 doctors by heart in the whole world if others will have basic income.
Hard work, hard knowledge can be got right now only with a great motivation of people to get money for living together with profession. So this world (when robots can not supply me with everything I need yet) needs to have poor people.
But to get the life with robots for everything everybody needs to earn money to buy them even when they will appear. That's the best way not to destroy our civilization since we didn't cross the line yet not to need humans.