This sounds like a useful corollary for a high income individual that should apply generally, but if you watch videos on the "death of the middle class" videos you'll learn that the middle class in America didn't actually die recently, its actually just as big as it ever was, it's just stuff like spending on cars and housing is wayyy more expensive than ever so even us well paid software people are functionally poorer than we should be.
https://youtu.be/0sj-8pjt9Xk
IRL the vast majority of these consumer spending things don't play a massively damaging role in the average consumers life / upward mobility... at least relative to history or other regions. But a few things do. When you start getting serious about personal finance people tend to obsess about the small less important things we're wasteful about. Mostly because it's more obvious locally and easy to feel guilty about (consumer electronics, clothes, restaurants, etc).
But in practice for healthy well employed workers 80-90% of the time self-imposed poverty comes down to two things: cars and renting housing.
Cars ranks #1 easily in terms of actionable things, if you asked 90% of middle class households making >$100k you'll find car loans/costs are easily the biggest burden on disposable income. People buy cars they can't afford and getting $30k+ loans plus the associated costs of nice cars (damaging them, insurance, etc) it becomes very apparently the biggest thing stopping someone from having extra money that could be invested in 10x+ more value like paying off high interest credit card loans (rather than adding another +interest car loan) or simply investing in better things like real estate, small businesses, personal development, stocks, etc etc.
The other elephant in the room that far, far outweighs spending on vanity consumerism is housing. This one involves plenty of personal responsibility but of all the things in Americans/western life this is the least to blame individuals.
Stopping Americans from buying stupid expensive cars is a very hard mostly social problem, but housing is something that could be solved much more simply through stuff like ending zoning and anti-NIMBY laws.
We could gain plenty from working on the smaller tier consumer stuff at the same time (every dollar really does matter and you don't know until you track it) but education about cars and gov action on increasing housing supply would be the most productive work in the short term.