In my opinion, expensive clothes and goods can be a choice, but it is not an indicator to see whether someone is rich or poor. even many rich people choose a simple lifestyle, while others may dress luxuriously to express themselves. Therefore, to judge someone poor or rich is not measured by what they wear.
I agree with you that buy good and expensive things is actually a choice and their are rich people that they are entitled to their opinion on how to dress simple while others love exotic lifestyle and many more so their is nothing more than doing what you enjoying doing most because their is a lot of people that will think that maybe its because of their personality so we just have learn to understand what people love. Their outfits that you can not even be able to predict what they worth if not that you are told.
Looking nice is just another way of making your self presentable, and those that do business and deals should know what am talking about because when you meet people that is exactly how they will judge you so you need to be addressed properly. Their are watches that you might not even know their worth if not that you know watches or cloths very well because they are always looking like normal outfits but very expensive and another things is that you don't expect me to be rich and not look nice i will try to make my self comfortable as much as I want what will now be the essence of making money when you can not even buy the things you like.
All this is going to be determined by the personality of that individual, and what they want, your point is totally valid you can not always judge by what they wear.