A narrative has developed, not least since the 2008/9 finance screw-up, that “green” is synonymous with privilege. It’s a narrative that suits the broadly consumerist status quo.
It’s propped up because concern for the broader environment isn’t toward the top of the hierarchy of needs (air, food, water, shelter etc.)
When capital generates mass anxiety over meeting fairly basic needs, even in a modern “recovering” economy, it is easy to generate a sneer against those with concerns beyond that. Caring about the planet thus gets presented as some sort of heresy against the working class. Some socialists are happy to tag along with this construct.
The more working class people believe it the more it becomes true as they are alienated from overt environmentalist politics and action, even if it’s their kids getting asthma etc and despite the facts that Green politics are pro poor (It’s also vital to remember that there is no economy without ecology)
Who promotes the lazy myth? Not working class people. Not environmentalists.
Yet for all this, my lived experience is that Green Party members and supporters are in similar-ish jobs / incomes or whatever to those in the Libdems, Labour and left parties that I know. I can comment less on UKIP or the tories but it could well be true in those cases too, or perhaps they are narrower still.