We are body and soul. So if one considers that the soul has a boundary, then it is worth pursuing the search ?! Being poor or wealthy is all to do with inner self. Those related to the soul and spiritual well being. Thus, if we acknowledge that we are composed of two main entities: the soul and the body, then making the soul rich is more worhtwhile, because the body will be ash....
Paul McKenna wrote a best seller called: "I CAN MAKE YOU RICH". It is worth reading.
1) If your household can sustain its living without physical labouring, you belong to the "capitalist" rich & wealthy class.
2) Otherwise (if stop working will bring you starvation or mortgage problems, thus not possible), you are proletarian, i.e. poor.
3) "Not poor" or middle-class is an irrelevant concept in the 21st century. You are either 1 or 2, regardless of how much you're paid a month. Only 1 and 2 is relevant to how one relates him/herself to the world, and all the other labels are useful only for marketing researches.
These are economic phenomenon and relative terms; above poverty-line with more comforts is not-poor, with more luxuries is rich and with more income and assets is wealthier.