Money is a fiat currency we use in modern society to bring us our wants and needs. If you like Jimmy Choo's shoes, then, yes, buy Jimmy Choo shoes. But, if you don't think it's worth your time, please keep that to yourself and don't impose that judgment on others. Your taste is different from theirs, and vice versa.
They may look like a model out of a Gucci magazine, but you can stick to your local brands if you like. Just let people be as they are. Same for those who think that someone should spend more on their items. You consider a Gucci bag is your money's worth, but that doesn't imply everyone else does.
If you do talk about how designer items and whether one should invest in them, please be kind towards others and help them understand that you respectively disagree with their opinion. It's easy for all of us to say money doesn't buy taste, and that is true. The way you dress, eat, and live your daily life comes about you and your life choices. Yes, the more money you have, the more likely you are going to spend it. But, there are individuals out there who spend even without having any safety money. So, I don't think it's just money.
Yes, you may belive many people are wasting their money out of nothing, but we shouldn't impose our judgment on them. I think it's best to ask them why they do it and have a peaceful discussion if you want to explain your opinion on the subject matter.
I have two takes on this idea. My first one is that money should be put to use, depending on the owner at the moment. So girl, if you want to invest in blow dry's, go for it! It's your money, so you decide it's use to you then and there. If you want to give a large sum of it to charity, go right ahead (I will also commend you for thinking about others from time to time)!
Another thing I do suggest is if you see this as an issue overall, try what you can to solve from your side before telling others what they should do. I am a firm believer in the idea that changes start with you. Humans are known for being flawed by nature. We can't demand others to support what we believe, especially if we don't even attempt to follow it.