You might call it unhelpful moralizing, but I would consider it helpful if it alerted people to the pretentious nature of their social signaling and got them back on track financially. Deferred gratification is an important lesson to learn.
I once went to a nutrionist and she ask what I eat for breakfast; I told her and she said "you know how many calories were in that bagel?" and I told her. She looked puzzled, then I told her "I wasn't fat because I was stupid"
Behaviors with food and even money are learned early on and until people choose to unlearn them; they will be fat and poor.
>Everyone know what kind of food to eat, they just don't.
I think the world you're looking for here is "ignorant". They know. Stupid is knowing what to do and still doing the exact opposite. And I point this out as a stupid person (about some things).
Unless they learned the "correct" behaviors early on. In that case they have the luxury of not thinking about the basics and expanding upon what they already know. Privilege comes in many forms.
If so, then getting the word out may actually help people make better decisions. If they still want the BMW for other reasons, fine.