This was based on a question that my economics professor in college had asked us. His question was more to the effect of “What’s a good/service people buy when they have a bit of money, then they stop buying or buy less of it when they get some more money, and then they start buying it again once they have even more money?” — feel free to answer that too.
My first thought was alcohol: lower class people might buy more of it to cope with their difficult situation, whereas upper class people have more money to spend on vices and luxuries such as alcohol. Not sure if this theory holds true.
The best answer I’ve been able to come up with is golf carts, at least in the US. It’s common to see lower class people drive golf carts around their trailer parks or neighborhoods, whereas middle class people rarely do that. An upper class person might live in a wealthy neighborhood with its own built-in golf course, or the person might even own their own golf course(s).
Some dubious investments, such as crypto or donations to certain social organizations or politicians might also qualify?
This is less of a specific good and more of a trend, but middle class people are more likely to buy bulk goods. Lower classes often don’t have the means to do so (space to store it and money to buy it, or access to places that sell in bulk) and higher classes simply don’t need to, or they buy luxury items that wouldn’t be sold in bulk.
Similarly, middle class people are less likely to shop at places with high markups, such as convenience stores.
The times when people shop would also see trends, with lower and higher classes doing more shopping midday on a Tuesday and middle class working people with average 9-5 office jobs being unable to do so.