They try to frame it in racial terms, but you’re right, it’s more of a class issue.
The left hates the idea of a middle class, because they love to indulge in their elitism. They love to have a huge difference between their lifestyle and that of the masses.
The existence of a middle class “stinks” to them, because there’s not that much difference in lifestyle (running water, sanitation, nutritious food, indoor climate control) between them and the middle class.
Seem to be tying it into Sustainability Movement/Agenda 21....