Where is the basis of this not enough resources for middle class life style?

Tell me, what is middle class life style anyway? If you are talking about the American consumerism middle class life style, sure, I think most educated people nowadays do not really like that form of life style, or find it actually comfortable.

And even if that's the style everyone wants to. With tech advancement, why cannot everyone afford that, while still keep the environment health and sustainable for human?

Please enlighten me...