Simply put, poor people buy for style and cool while rich people buy for quality, utility and prestige.
This goes back to how to treat money in life, in the sense that poor people are not not allowed to buy expensive goods and indulge in what the rich do, only they do not have enough to live much longer but they force it to fulfill their desires not their needs.
Yes the way money is spent by the classes and category of people can't be measured overtime but this happens this way because people try to suit in with their preference of their demands and they can't do more than that, the rich can spend on luxury and quality stuff cause they can afford it and the poor in the other hand will always go for what they can afford in a low quality and thus is the distinctive difference between both the rich and the poor.
Maybe it's true but what I see that rich people or people who become rich do not necessarily buy luxury goods for themselves, they always have logical reasons for buying goods for the benefit of their business, you may need to pay attention and listen to many people who want to maintain their wealth and indeed the ordinary rich people will have different behavior in using money you can see from them shopping, while poor people from most of them buy goods that are actually more than what they can get from their work.