Life is more expensive for poor people. What you say might be true, but can most people actually afford the $200 toaster? Maybe they can in the most literal sense, there's $400 in their account, but they can't justify the expense.

Good ol Sam Vimes put it fairly well in the book Men at Arms:

The reason that the rich were so rich, Vimes reasoned, was because they managed to spend less money.

Take boots, for example. He earned thirty-eight dollars a month plus allowances. A really good pair of leather boots cost fifty dollars. But an affordable pair of boots, which were sort of OK for a season or two and then leaked like hell when the cardboard gave out, cost about ten dollars. Those were the kind of boots Vimes always bought, and wore until the soles were so thin that he could tell where he was in Ankh-Morpork on a foggy night by the feel of the cobbles.

But the thing was that good boots lasted for years and years. A man who could afford fifty dollars had a pair of boots that’d still be keeping his feet dry in ten years’ time, while the poor man who could only afford cheap boots would have spent a hundred dollars on boots in the same time and would still have wet feet.

-Men at Arms

Shopping is a hell of a drug

Because they were conditioned to be that way.