I admire that a small interaction can trigger this much reflection. Also, as an aside, I still often think of you whenever I buy a Macchiato. "I wonder if kb would think this one tastes like battery acid."
I once read an article that argued that the difference between people who aren't good with money and those that are comes down to how they perceive it.
The former view it as fuel for their lifestyle. They get paid and can get takeaway food again, go out drinking multiple times a week, and buy that PS4 game. And when the tank is empty they live on ramen until the next paycheck fills it up again.
The latter view it as building blocks to the kind of life they want to live. So if they want to be the kind of person who can buy a quality $400 backpack, they budget, save, and live modestly. Eventually, the time comes when they afford the backpack without worrying whether it means they're going to get scurvy.
I think this difference in perception feeds into how the former view the latter when they buy an expensive item. All the person who's bad with money sees some is out-of-touch, bougie asshole frittering $400 worth of premium life fuel on a bag. "If I can salvage a ratty old bag off the floor and replace the parts that keep breaking, why can't they?" And the resentment builds. Never mind the fact that any normal person has to carefully build their life in order to safely afford such an item. Never mind the fact that they bought it for its quality craftsmanship and ethics and not purely as a status symbol. Never mind that it will last a lifetime and still be in as good a condition as the day it was bought. There's just a fundamental perception gap which becomes filled with negativity.
I'm not sure if I'm completely committed to this point of view yet. I know it generalises and misses out on some nuance. But I think it stands up to some scrutiny.