The reason "We (USamericans) should reduce our personal consumption of resources to save the planet!" won't change anything, is that there is no "we."

The average American does X amount of unnecessary shopping, but collapsing the wide range of wealth inequality into an average creates a vague call to action that sufficiently motivates 0 people.

Poor people feel guilty about buying stuff already. Even essential stuff. They have very little ability to adjust the amount they consume, and any adjustments that are possible would be almost negligible.

The moderately affluent and up vastly overestimate the impact of small adjustments to their lifestyle, and think of denying themselves any indulgence as extreme frugality. This is often the group that uses the "we" pronoun in the statement "We should consume less."

Most of the USA's carbon emissions come from heating and cooling and from cars. Since homelessness is treated as a crime, houses are not made sustainably or constructed smaller than a certain size, and it is virtually impossible to work or obtain basic needs without a car, there is a very solid and nearly impenetrable bottom to the scale of individual consumption.

So much consumption is near 100% impossible to opt out of, which means of course that the money that goes to it is never really yours, it just happens to pass through you on its way to its true destination.

This is obscured by the fact that the more privileged can ride a cushioned elevator below that bottom, play for as long as it takes for them to feel good about themselves, and take the elevator back up, and then write an article saying "See! I lived on 3 cents a day/lived in a 100sqft house/didn't use electricity for a week, and here's what I learned!"

Sure, you tried living a frugal life for a while. But you never doubted that the elevator would be there to take you back when you were tired of playing. You never felt the Fear. That's why you learned nothing.